diff --git a/.github/workflows/test-in-nix.yml b/.github/workflows/test-in-nix.yml
new file mode 100644
index 00000000..49c1b329
--- /dev/null
+++ b/.github/workflows/test-in-nix.yml
@@ -0,0 +1,47 @@
+name: test in Nix
+
+on:
+  - push
+  - pull_request
+
+jobs:
+  tests-in-nix:
+    name: Tests in Nix
+    strategy:
+      fail-fast: false
+      matrix:
+        os:
+          - ubuntu-latest
+          - macos-latest
+        ocaml-version:
+          - 4_11
+          - 4_12
+          - 4_13
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+
+      - name: Setup Nix
+        uses: cachix/install-nix-action@v15
+        with:
+          nix_path: nixpkgs=channel:nixos-21.11
+          extra_nix_config: |
+            trusted-public-keys = cache.nixos.org-1:6NCHdD59X431o0gWypbMrAURkbJ16ZPMQFGspcDShjY=
+            substituters = https://cache.nixos.org/
+            max-jobs = auto
+            cores = 0
+
+      - name: Build
+        run: |
+          nix-shell --argstr ocamlVersion ${{ matrix.ocaml-version }} --run "dune build"
+
+      - name: Test
+        run: |
+          nix-shell --argstr ocamlVersion ${{ matrix.ocaml-version }} --run "dune runtest"
+
+      - name: Examples
+        run: |
+          nix-shell --argstr ocamlVersion ${{ matrix.ocaml-version }} --run "dune examples"
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index dc70a5fc..1609afee 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -1,4 +1,4 @@
-name: build
+name: test
 
 on:
   - push
diff --git a/.gitignore b/.gitignore
index 151710ae..d6b9425b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,3 +7,5 @@ lib_test/tests_
 *.docdir
 .merlin
 *.install
+
+/result
diff --git a/README.md b/README.md
index 54af50af..f89029fb 100644
--- a/README.md
+++ b/README.md
@@ -106,6 +106,12 @@ opam pin add -n httpaf .
 opam install --deps-only httpaf
 ```
 
+If you use [Nix](https://nixos.org/), you can enter `nix-shell`, which contains dev dependencies including ocaml-lsp.
+
+```bash
+nix-shell shell.nix
+```
+
 After this, you may install a development version of the library using the
 install command as usual.
 
diff --git a/default.nix b/default.nix
new file mode 100644
index 00000000..e5615766
--- /dev/null
+++ b/default.nix
@@ -0,0 +1,10 @@
+{ pkgs ? import <nixpkgs> {}
+, ocamlVersion ? import ./nix/ocamlDefaultVersion.nix
+, opam2nix ?
+    pkgs.callPackage ./nix/opam2nix.nix {
+      inherit pkgs;
+      ocamlPackagesOverride = pkgs.ocaml-ng."ocamlPackages_${ocamlVersion}";
+
+} }:
+
+pkgs.callPackage ./nix { inherit ocamlVersion opam2nix; }
diff --git a/nix/default.nix b/nix/default.nix
new file mode 100644
index 00000000..6ce85618
--- /dev/null
+++ b/nix/default.nix
@@ -0,0 +1,36 @@
+{ pkgs, lib, stdenv, ocamlVersion, opam2nix }:
+let
+  inherit (lib) strings;
+  args = {
+    inherit (pkgs.ocaml-ng."ocamlPackages_${ocamlVersion}") ocaml;
+    src =
+      let ignores = pkgs.lib.strings.fileContents ../.gitignore;
+      in pkgs.nix-gitignore.gitignoreSourcePure ignores ../.;
+  };
+
+  opam-selection = opam2nix.build (args // {
+    selection = "${./opam-selection_${ocamlVersion}.nix}";
+  });
+
+  localPackages =
+    let contents = builtins.attrNames (builtins.readDir ../.);
+    in builtins.filter (strings.hasSuffix ".opam") contents;
+
+  # list of dependencies with "with-test" flag manually
+  testPackageNames = [ "alcotest" ];
+  testPackages =
+    builtins.map (name: builtins.getAttr name opam-selection) testPackageNames;
+
+  resolve = opam2nix.resolve (args // {
+    selection = "./nix/opam-selection_${ocamlVersion}.nix";
+  }) (localPackages ++ testPackageNames);
+
+
+in (builtins.listToAttrs (builtins.map (fname:
+  let packageName = strings.removeSuffix ".opam" fname;
+  in {
+    name = packageName;
+    value = builtins.getAttr packageName opam-selection;
+  }) localPackages)) // {
+    inherit resolve opam-selection testPackages;
+  }
diff --git a/nix/ocamlDefaultVersion.nix b/nix/ocamlDefaultVersion.nix
new file mode 100644
index 00000000..3c83a22d
--- /dev/null
+++ b/nix/ocamlDefaultVersion.nix
@@ -0,0 +1 @@
+"4_13"
diff --git a/nix/opam-selection_4_11.nix b/nix/opam-selection_4_11.nix
new file mode 100644
index 00000000..9bff2684
--- /dev/null
+++ b/nix/opam-selection_4_11.nix
@@ -0,0 +1,1822 @@
+### This file is generated by opam2nix.
+
+self:
+let
+    lib = self.lib;
+    pkgs = self.pkgs;
+    selection = self.selection;
+    repoPath = self.repoPath;
+    repos = 
+    {
+      opam-repository = 
+      rec {
+        fetch = 
+        {
+          owner = "ocaml";
+          repo = "opam-repository";
+          rev = "448eb8eb91b9e5db70daeb6fff52877ff6d72791";
+          sha256 = "1653jc4886z7spwkbfpblrjjwsfbwd0xzggrmrxfjps5a1zwi88q";
+        };
+        src = (pkgs.fetchFromGitHub) fetch;
+      };
+    };
+in
+{
+  format-version = 4;
+  inherit repos;
+  ocaml-version = "4.11.2";
+  selection = 
+  {
+    alcotest = 
+    {
+      pname = "alcotest";
+      version = "1.5.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/mirage/alcotest/releases/download/1.5.0/alcotest-js-1.5.0.tbz";
+        sha256 = "0v4ghia378g3l53r61fj98ljha0qxl82xp26y9frjy1dw03ija2l";
+      };
+      opamInputs = 
+      {
+        inherit (selection) uutf stdlib-shims re ocaml-syntax-shims ocaml fmt
+        dune cmdliner astring;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/alcotest/alcotest.1.5.0";
+        hash = "sha256:0rj1wwjawpls9y4dbq2fkw5pa2484vw5jdrw4w54ypafy8qalhk0";
+      };
+    };
+    angstrom = 
+    {
+      pname = "angstrom";
+      version = "0.15.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/angstrom/archive/0.15.0.tar.gz";
+        sha256 = "01cjjal8vjsm225v9y0q6ixam8k5f821rcr6yix6i9nzs84aq6gi";
+      };
+      opamInputs = 
+      {
+        inherit (selection) result ocaml-syntax-shims ocaml dune bigstringaf;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/angstrom/angstrom.0.15.0";
+        hash = "sha256:07ryik3g3hz79hnfdwxdh2jsw3cmbgygjs7mjdw07p927wkd83k9";
+      };
+    };
+    astring = 
+    {
+      pname = "astring";
+      version = "0.8.5";
+      src = pkgs.fetchurl 
+      {
+        url = "https://erratique.ch/software/astring/releases/astring-0.8.5.tbz";
+        sha256 = "1ykhg9gd3iy7zsgyiy2p9b1wkpqg9irw5pvcqs3sphq71iir4ml6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) topkg ocamlfind ocamlbuild ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/astring/astring.0.8.5";
+        hash = "sha256:1djnad9sq12idlakj069xvwm2nn7wqm137pqbxxai5frkgi08x74";
+      };
+    };
+    async = 
+    {
+      pname = "async";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async-v0.14.0.tar.gz";
+        sha256 = "0r6w2df5wn4xjhkhscnxrriwg19qwlxcss3srj4j5fg33jqbgwkl";
+      };
+      opamInputs = 
+      {
+        inherit (selection) textutils ppx_jane ocaml dune core_kernel core
+        async_unix async_rpc_kernel async_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async/async.v0.14.0";
+        hash = "sha256:085dsrvxlk1qmszhhi45h7z6w85fz7ik468ylx71ap3977cpayha";
+      };
+    };
+    async_kernel = 
+    {
+      pname = "async_kernel";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async_kernel-v0.14.0.tar.gz";
+        sha256 = "13k0dsbvw69jl6ckqrvigdvjffcqy778nish3370kl9lkmp0c49m";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async_kernel/async_kernel.v0.14.0";
+        hash = "sha256:185cp75vc3sgirs34xxmy5ggnvjpbj8sxxnl3p5n1v2kldf7n28j";
+      };
+    };
+    async_rpc_kernel = 
+    {
+      pname = "async_rpc_kernel";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async_rpc_kernel-v0.14.0.tar.gz";
+        sha256 = "1xrrpmhwhav3prr382q088h8sn7dax2s58hkwcv4ilcwx4zbmyk8";
+      };
+      opamInputs = 
+      {
+        inherit (selection) protocol_version_header ppx_jane ocaml dune
+        core_kernel async_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async_rpc_kernel/async_rpc_kernel.v0.14.0";
+        hash = "sha256:1l3wa564cqhjc47cwqf3a51d44cgzijmvrhjm0z0jakm6sj0rmww";
+      };
+    };
+    async_unix = 
+    {
+      pname = "async_unix";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async_unix-v0.14.0.tar.gz";
+        sha256 = "1f9jv97xs3lgw4n7p7b95nixldh47gpbh6shcnsf0ccjxgnwx5xf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel core async_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async_unix/async_unix.v0.14.0";
+        hash = "sha256:095m4yxgvxg2cwqa2jas6lc16w1rllzwg7v29kgbbgwlg3l91lv7";
+      };
+    };
+    base = 
+    {
+      pname = "base";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/base/archive/v0.14.2.tar.gz";
+        sha256 = "095zbz0bqrmhgw62jyhb51kqp89kph1cfcpr5ww94slr5rldpj7i";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 ocaml dune-configurator dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base/base.v0.14.2";
+        hash = "sha256:004ypm5lr9mp7glgfggi47x8h644f9z7xrx5gahsx1l82b566frv";
+      };
+    };
+    base-bytes = 
+    {
+      pname = "base-bytes";
+      version = "base";
+      src = null;
+      opamInputs = {
+                     inherit (selection) ocamlfind ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base-bytes/base-bytes.base";
+        hash = "sha256:0a68lmbf68jgm1i3b59j2sc3ha9yhv4678f9mfwwvczw88prq7l3";
+      };
+    };
+    base-threads = 
+    {
+      pname = "base-threads";
+      version = "base";
+      src = null;
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base-threads/base-threads.base";
+        hash = "sha256:1c4bpyh61ampjgk5yh3inrgcpf1z1xv0pshn54ycmpn4dyzv0p2x";
+      };
+    };
+    base-unix = 
+    {
+      pname = "base-unix";
+      version = "base";
+      src = null;
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base-unix/base-unix.base";
+        hash = "sha256:0mpsvb7684g723ylngryh15aqxg3blb7hgmq2fsqjyppr36iyzwg";
+      };
+    };
+    base_bigstring = 
+    {
+      pname = "base_bigstring";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/base_bigstring-v0.14.0.tar.gz";
+        sha256 = "1fhldk58w56ixkin763kpic512xvkkf9b4mrnjfsbm8in75kzndq";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base_bigstring/base_bigstring.v0.14.0";
+        hash = "sha256:0yn51npq4fwi9nllfhq2r3kkb17pg3igvvjgblac1g3v0nmhj6c4";
+      };
+    };
+    base_quickcheck = 
+    {
+      pname = "base_quickcheck";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/base_quickcheck/archive/v0.14.1.tar.gz";
+        sha256 = "0n5h0ysn593awvz4crkvzf5r800hd1c55bx9mm9vbqs906zii6mn";
+      };
+      opamInputs = 
+      {
+        inherit (selection) splittable_random ppxlib ppx_sexp_value
+        ppx_sexp_message ppx_let ppx_fields_conv ppx_base ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base_quickcheck/base_quickcheck.v0.14.1";
+        hash = "sha256:0lxxagkyg1jh0x7bbps1972bid51a82m1h2x3nyz342dnsy4k6h1";
+      };
+    };
+    bigarray-compat = 
+    {
+      pname = "bigarray-compat";
+      version = "1.0.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/mirage/bigarray-compat/archive/v1.0.0.tar.gz";
+        sha256 = "1bpmmnxb1yx72aqlbdaqfl18rgz1cq9cf6cqvnfl88mz5dfr4x0d";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/bigarray-compat/bigarray-compat.1.0.0";
+        hash = "sha256:0mcg8csmd60ph17vam1s8xjsl9kp6k77i3mnkbxy0jvkn49m4a0k";
+      };
+    };
+    bigstringaf = 
+    {
+      pname = "bigstringaf";
+      version = "0.8.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/bigstringaf/archive/0.8.0.tar.gz";
+        sha256 = "06w66xnqgv8r92x50b3q6xrymry6fviyj572dw7y76cqdzfph18z";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune conf-pkg-config
+        bigarray-compat;
+        ocaml-freestanding = selection.ocaml-freestanding or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/bigstringaf/bigstringaf.0.8.0";
+        hash = "sha256:0q3v7v83pj1rf7qzqj5silkx0s8sjpkwjzkvnmnqkyp4aljqnlnb";
+      };
+    };
+    bin_prot = 
+    {
+      pname = "bin_prot";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/bin_prot-v0.14.0.tar.gz";
+        sha256 = "1f1ng6cixi3ci0nb765yfzqk9b3s752hy1i3702kh59gni1psycp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_variants_conv ppx_sexp_conv ppx_optcomp
+        ppx_fields_conv ppx_custom_printf ppx_compare ocaml dune
+        base;
+        mirage-xen-ocaml = selection.mirage-xen-ocaml or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/bin_prot/bin_prot.v0.14.0";
+        hash = "sha256:17ylwhh1kv9klavfag20n4g3175i7nmljbdj12z9yiqm4da3r4rk";
+      };
+    };
+    cmdliner = 
+    {
+      pname = "cmdliner";
+      version = "1.0.4";
+      src = pkgs.fetchurl 
+      {
+        url = "http://erratique.ch/software/cmdliner/releases/cmdliner-1.0.4.tbz";
+        sha256 = "1h04q0zkasd0mw64ggh4y58lgzkhg6yhzy60lab8k8zq9ba96ajw";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/cmdliner/cmdliner.1.0.4";
+        hash = "sha256:05qlm4yp6124w2z10dpdchldfrmgmcr6h31rnxp8qs8mk0xzx48z";
+      };
+    };
+    conf-pkg-config = 
+    {
+      pname = "conf-pkg-config";
+      version = "2";
+      src = null;
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/conf-pkg-config/conf-pkg-config.2";
+        hash = "sha256:1rli6809glz5g9xwp4wsjidc39za4n58xcpkamy6fymfnqha225n";
+      };
+      buildInputs = [ (pkgs.pkgconfig) ];
+    };
+    core = 
+    {
+      pname = "core";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/core/archive/v0.14.1.tar.gz";
+        sha256 = "1862zsk85i00vsv2chgb156b1chp8f7p508hsz6sadjx6h98q5cc";
+      };
+      opamInputs = 
+      {
+        inherit (selection) timezone spawn sexplib ppx_jane ocaml jst-config
+        dune core_kernel base-threads;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/core/core.v0.14.1";
+        hash = "sha256:13hkxn24szh9j0xl6m65k9cg8blqh44yb0nz9m5wrfbyfn8zd1hd";
+      };
+      buildInputs = [ (pkgs.linux-headers or null) ];
+    };
+    core_kernel = 
+    {
+      pname = "core_kernel";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/core_kernel/archive/v0.14.2.tar.gz";
+        sha256 = "0jyf08i9wzg3yf32f158i6n9gm751bk8zj7xqx79jnnkchwkbxb6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) variantslib typerep time_now stdio
+        splittable_random sexplib ppx_sexp_message ppx_sexp_conv ppx_optcomp
+        ppx_jane ppx_inline_test ppx_hash ppx_base ppx_assert ocaml
+        jst-config jane-street-headers fieldslib dune bin_prot
+        base_quickcheck base_bigstring base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/core_kernel/core_kernel.v0.14.2";
+        hash = "sha256:09c7k6m1vm8jhqfivn8w663v362qwjf6cb5xlzijd0sjgh1dwai5";
+      };
+    };
+    cppo = 
+    {
+      pname = "cppo";
+      version = "1.6.8";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-community/cppo/archive/v1.6.8.tar.gz";
+        sha256 = "0lxy4xkkkwgs1cj6d9lyzsqi9f6fc9r6cir5imi7yjqrpd86s1by";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune base-unix;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/cppo/cppo.1.6.8";
+        hash = "sha256:0pzd8irqkkkpfgw8nq9d21z9rj5m3qlzixyb7ybfy4b1fwh3n8bp";
+      };
+    };
+    csexp = 
+    {
+      pname = "csexp";
+      version = "1.5.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-dune/csexp/releases/download/1.5.1/csexp-1.5.1.tbz";
+        sha256 = "00mc19f89pxpmjl62862ya5kjcfrl8rjzvs00j05h2m9bw3f81fn";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/csexp/csexp.1.5.1";
+        hash = "sha256:01lc95kz13gpki4xazyh6n20kv1g9inyb5myv240wl2n9v50z8fl";
+      };
+    };
+    dune = 
+    {
+      pname = "dune";
+      version = "2.9.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/dune/releases/download/2.9.2/dune-site-2.9.2.tbz";
+        sha256 = "0ivl5r9diky8r1rfka7427kc3lh168mrz0ywdxgv8y5rgx8crrxq";
+      };
+      opamInputs = 
+      {
+        inherit (selection) base-unix
+        base-threads;
+        ocamlfind-secondary = selection.ocamlfind-secondary or null;
+        ocaml = selection.ocaml or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/dune/dune.2.9.2";
+        hash = "sha256:0qzzy2kn29ww9ryl2fvhkph9lmc112yr86xn8r8s9rbaz2zfkm6x";
+      };
+    };
+    dune-configurator = 
+    {
+      pname = "dune-configurator";
+      version = "2.9.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/dune/releases/download/2.9.1/dune-2.9.1.tbz";
+        sha256 = "09lzq04b642iy0ljp59p32lgk3q8iphjh8fkdp69q29l5frgwx5k";
+      };
+      opamInputs = 
+      {
+        inherit (selection) result ocaml dune csexp;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/dune-configurator/dune-configurator.2.9.1";
+        hash = "sha256:1aik9w82r8vbb9fsfphpb0vam68s19ggkxprnqr99ygyalp2b71j";
+      };
+    };
+    faraday = 
+    {
+      pname = "faraday";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune bigstringaf;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday/faraday.0.8.1";
+        hash = "sha256:1gk9zcifglbfnkjhndd96xf6bfp5ldmrpvvy3daidfd07l56vr96";
+      };
+    };
+    faraday-async = 
+    {
+      pname = "faraday-async";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml faraday dune core async;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday-async/faraday-async.0.8.1";
+        hash = "sha256:0vwz2qn0mmv8n4xl1jcjghnj0cfy66yq621mmhd0vgnfqyw4sysm";
+      };
+    };
+    faraday-lwt = 
+    {
+      pname = "faraday-lwt";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml lwt faraday dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday-lwt/faraday-lwt.0.8.1";
+        hash = "sha256:14nrlva43l45wp71rbyk2fb9nk43krqp292wzrlmc8ip19pc8y9p";
+      };
+    };
+    faraday-lwt-unix = 
+    {
+      pname = "faraday-lwt-unix";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml lwt faraday-lwt dune base-unix;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday-lwt-unix/faraday-lwt-unix.0.8.1";
+        hash = "sha256:1zfzrrbfdvw4mbmp5alkv8bmhcsfr5nillb2nj6p49fab347182m";
+      };
+    };
+    fieldslib = 
+    {
+      pname = "fieldslib";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/fieldslib-v0.14.0.tar.gz";
+        sha256 = "10n5y376fb5jgqk9h8vq158rm1b36h9lzh6p11q33h6xgvb1v6n3";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/fieldslib/fieldslib.v0.14.0";
+        hash = "sha256:1gsrbs4x45k4bp1zih9c6db3axhaiy91knac6bk6hpgv9sjalicm";
+      };
+    };
+    fmt = 
+    {
+      pname = "fmt";
+      version = "0.9.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://erratique.ch/software/fmt/releases/fmt-0.9.0.tbz";
+        sha256 = "0q8j2in2473xh7k4hfgnppv9qy77f2ih89yp6yhpbp92ba021yzi";
+      };
+      opamInputs = 
+      {
+        inherit (selection) topkg ocamlfind ocamlbuild
+        ocaml;
+        cmdliner = selection.cmdliner or null;
+        base-unix = selection.base-unix or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/fmt/fmt.0.9.0";
+        hash = "sha256:1czh5i3i4mkf9xfasji3v7n821qmnnandlklh67ali0x87brldny";
+      };
+    };
+    httpaf = 
+    {
+      pname = "httpaf";
+      version = "development";
+      src = self.directSrc "httpaf";
+      opamInputs = 
+      {
+        inherit (selection) result ocaml faraday dune bigstringaf angstrom;
+      };
+      opamSrc = "httpaf.opam";
+    };
+    httpaf-async = 
+    {
+      pname = "httpaf-async";
+      version = "development";
+      src = self.directSrc "httpaf-async";
+      opamInputs = 
+      {
+        inherit (selection) ocaml httpaf faraday-async dune async;
+      };
+      opamSrc = "httpaf-async.opam";
+    };
+    httpaf-lwt-unix = 
+    {
+      pname = "httpaf-lwt-unix";
+      version = "development";
+      src = self.directSrc "httpaf-lwt-unix";
+      opamInputs = 
+      {
+        inherit (selection) ocaml lwt httpaf faraday-lwt-unix dune;
+      };
+      opamSrc = "httpaf-lwt-unix.opam";
+    };
+    jane-street-headers = 
+    {
+      pname = "jane-street-headers";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/jane-street-headers-v0.14.0.tar.gz";
+        sha256 = "028yxb4h3iy025iy89v8653m5brh7flrjshghs4x99pd690pmfs7";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/jane-street-headers/jane-street-headers.v0.14.0";
+        hash = "sha256:1w6zjjmyszk9pax139rkxb3vx0w23w0pfd46bddfyfkxq2rbwsvf";
+      };
+    };
+    jst-config = 
+    {
+      pname = "jst-config";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/jst-config/archive/refs/tags/v0.14.1.tar.gz";
+        sha256 = "0wdjs0lvc5wbggh27cf490jarfibrrb5xxsrigg41m32kjkbijm4";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio ppx_assert ocaml dune-configurator dune
+        base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/jst-config/jst-config.v0.14.1";
+        hash = "sha256:0myym84b9yx4vqa0ml0zf3cx6rms3g5dv704vhf5bpr7jnqz0qcb";
+      };
+    };
+    lwt = 
+    {
+      pname = "lwt";
+      version = "5.5.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocsigen/lwt/archive/refs/tags/5.5.0.tar.gz";
+        sha256 = "15gr6nhhfjyh91v9chvm6j7vnp1hhc60y3plgvcgl5yl5k7xbbj9";
+      };
+      opamInputs = 
+      {
+        inherit (selection) seq result ocplib-endian ocaml mmap
+        dune-configurator dune
+        cppo;
+        ocaml-syntax-shims = selection.ocaml-syntax-shims or null;
+        conf-libev = selection.conf-libev or null;
+        base-unix = selection.base-unix or null;
+        base-threads = selection.base-threads or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/lwt/lwt.5.5.0";
+        hash = "sha256:0iadlycd4q93lsk07k9zaimlysgd38sj6v50dc3cb491vl0icipz";
+      };
+    };
+    mmap = 
+    {
+      pname = "mmap";
+      version = "1.1.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/mirage/mmap/releases/download/v1.1.0/mmap-v1.1.0.tbz";
+        sha256 = "0l6waidal2n8mkdn74avbslvc10sf49f5d889n838z03pra5chsc";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/mmap/mmap.1.1.0";
+        hash = "sha256:1snhaf6mixmmb49gcin5wmbz4bfjz406mip4556lids8ajm22ibh";
+      };
+    };
+    num = 
+    {
+      pname = "num";
+      version = "1.4";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/num/archive/v1.4.tar.gz";
+        sha256 = "090gl27g84r3s2b12vgkz8fp269jqlrhx4lpg7008yviisv8hl01";
+      };
+      opamInputs = {
+                     inherit (selection) ocamlfind ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/num/num.1.4";
+        hash = "sha256:04wb8ww165lsifn36jcrxw5zs87id5kib6rilq6zh6qhzvij88pf";
+      };
+    };
+    ocaml = 
+    {
+      pname = "ocaml";
+      version = "4.11.2";
+      src = null;
+      opamInputs = 
+      {
+        inherit (selection)
+        ocaml-config;
+        ocaml-variants = selection.ocaml-variants or null;
+        ocaml-system = selection.ocaml-system or null;
+        ocaml-base-compiler = selection.ocaml-base-compiler or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml/ocaml.4.11.2";
+        hash = "sha256:14clfk687d596dyhfblf9sljbk31937rrnyx2nqi7ii52qwknn5x";
+      };
+    };
+    ocaml-base-compiler = 
+    {
+      pname = "ocaml-base-compiler";
+      version = "4.11.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/ocaml/archive/4.11.2.tar.gz";
+        sha256 = "02day17rxrd0vla89mxl1yac657d1hs0lxspj8sd58ygyrl2ljh4";
+      };
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-base-compiler/ocaml-base-compiler.4.11.2";
+        hash = "sha256:0zaxk9ndzqf392h8arbl11qdllm0aljgahzam9ql2mq41pccpfdg";
+      };
+    };
+    ocaml-compiler-libs = 
+    {
+      pname = "ocaml-compiler-libs";
+      version = "v0.12.4";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ocaml-compiler-libs/releases/download/v0.12.4/ocaml-compiler-libs-v0.12.4.tbz";
+        sha256 = "0q3pl20pkx410gw9g4m26qq6dmzi9qan2dqlga6c2ifc6pnckjaf";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-compiler-libs/ocaml-compiler-libs.v0.12.4";
+        hash = "sha256:1blynia10j8vyj559kcvc7ic69zq6qjjn092fcsjzfw6czd8ya2c";
+      };
+    };
+    ocaml-config = 
+    {
+      pname = "ocaml-config";
+      version = "1";
+      src = null;
+      opamInputs = 
+      {
+        ocaml-variants = selection.ocaml-variants or null;
+        ocaml-system = selection.ocaml-system or null;
+        ocaml-base-compiler = selection.ocaml-base-compiler or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-config/ocaml-config.1";
+        hash = "sha256:1gc3pyhb64j8a91bgbpy9fzljpb1ps2ylgw31ldx879vdkk46nhp";
+      };
+    };
+    ocaml-syntax-shims = 
+    {
+      pname = "ocaml-syntax-shims";
+      version = "1.0.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-ppx/ocaml-syntax-shims/releases/download/1.0.0/ocaml-syntax-shims-1.0.0.tbz";
+        sha256 = "1j7848khli4p7j8i2kmnvhdnhcwhy3zgdpf5ds5ic30ax69y3cl9";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-syntax-shims/ocaml-syntax-shims.1.0.0";
+        hash = "sha256:0qnm1db0298yqcn6j9fmb0l4gr5nhcar8plskj39917invyamgd2";
+      };
+    };
+    ocamlbuild = 
+    {
+      pname = "ocamlbuild";
+      version = "0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/ocamlbuild/archive/0.14.0.tar.gz";
+        sha256 = "0y1fskw9rg2y1zgb7whv3v8v4xw04svgxslf3856q2aqd7lrrcl7";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocamlbuild/ocamlbuild.0.14.0";
+        hash = "sha256:1r5qnrcxfypzyvjvb3zd9f66kr5ldxdl3g9rsi3pb6040krqb5w7";
+      };
+    };
+    ocamlfind = 
+    {
+      pname = "ocamlfind";
+      version = "1.9.3";
+      src = pkgs.fetchurl 
+      {
+        url = "http://download.camlcity.org/download/findlib-1.9.3.tar.gz";
+        sha256 = "0hfcwamcvinmww59b5i4yxbf0kxyzkp5qv3d1c7ybn9q52vgq463";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml;
+        graphics = selection.graphics or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocamlfind/ocamlfind.1.9.3";
+        hash = "sha256:1wq1lkw3rpgilprlakznsxxf60mcidn3fzi3vjrgjdrnnp9hvh19";
+      };
+    };
+    ocplib-endian = 
+    {
+      pname = "ocplib-endian";
+      version = "1.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/OCamlPro/ocplib-endian/archive/refs/tags/1.2.tar.gz";
+        sha256 = "085kskr0cxcnv2d62n3jq1r273p7giisy56zfl26mm7amvl79blp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune cppo base-bytes;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocplib-endian/ocplib-endian.1.2";
+        hash = "sha256:1jldvb471gyhkrzwfvqg722l3a8dc37hhhyas66skjzfmqyi2pnh";
+      };
+    };
+    octavius = 
+    {
+      pname = "octavius";
+      version = "1.2.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-doc/octavius/archive/v1.2.2.tar.gz";
+        sha256 = "1bg0fcm7haqxvx5wx2cci0mbbq0gf1vw9fa4kkd6jsriw1611jga";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/octavius/octavius.1.2.2";
+        hash = "sha256:0bagilkanfjyi56hrk9dw43xs6zry9p8n3l55r3d58v5hz2xsbwl";
+      };
+    };
+    parsexp = 
+    {
+      pname = "parsexp";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/parsexp/archive/refs/tags/v0.14.2.tar.gz";
+        sha256 = "0c7jl6sqfawqpvbhci8vyyhgvcyd3lw5lj3jcf5f1p6w1177xqgn";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/parsexp/parsexp.v0.14.2";
+        hash = "sha256:1fqnxdr1pgxmada77hkhyyr7yybpv2f810shnhvhkpw15h58azx1";
+      };
+    };
+    ppx_assert = 
+    {
+      pname = "ppx_assert";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_assert-v0.14.0.tar.gz";
+        sha256 = "1l2rr4jz2q5b35ryn2z146z7m9v6k8krp5gpn8ilib66mnz5zx15";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_here ppx_compare
+        ppx_cold ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_assert/ppx_assert.v0.14.0";
+        hash = "sha256:1ry1bqssjw5lc7h0x2cc7f8rmz807j5l7029lxd4i12vgq91x5km";
+      };
+    };
+    ppx_base = 
+    {
+      pname = "ppx_base";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_base-v0.14.0.tar.gz";
+        sha256 = "0b7a3fmi90jk8paz0g36yzaq670fbnrbi1j8r5ibh9wbcfli7ji6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_js_style ppx_hash
+        ppx_enumerate ppx_compare ppx_cold ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_base/ppx_base.v0.14.0";
+        hash = "sha256:1n66x8xl2n0qbq1g0b1l3nsdqlb3czj5w509riwqdgz11fyrzi25";
+      };
+    };
+    ppx_bench = 
+    {
+      pname = "ppx_bench";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_bench/archive/v0.14.1.tar.gz";
+        sha256 = "1jr3cf4zsk894x64c8ir9ap9l412q35b2605pr7flrlxbm4vkf3f";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_inline_test ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_bench/ppx_bench.v0.14.1";
+        hash = "sha256:0r17lcfhxd14ihbbhqjqjmx26ig4xf62dmc2pblg7flzcf4k64dp";
+      };
+    };
+    ppx_bin_prot = 
+    {
+      pname = "ppx_bin_prot";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_bin_prot-v0.14.0.tar.gz";
+        sha256 = "0wa2jmvm2k88b37pbcafy1mdf5iaip0yxg5dw774sbh28nm08m2s";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_here ocaml dune bin_prot base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_bin_prot/ppx_bin_prot.v0.14.0";
+        hash = "sha256:0rsbhajm4927f1798baalwf3f7f5vs8jy27bxd6rhhybnvqjxyj9";
+      };
+    };
+    ppx_cold = 
+    {
+      pname = "ppx_cold";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_cold-v0.14.0.tar.gz";
+        sha256 = "1madfzhpir9amnxmg530n70vll0jrl59vyp71miji73i6b9sy6n2";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_cold/ppx_cold.v0.14.0";
+        hash = "sha256:0g566vskiblrxr246c3s26rlzxciln518fr4f6d8lid63qgrgnfm";
+      };
+    };
+    ppx_compare = 
+    {
+      pname = "ppx_compare";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_compare-v0.14.0.tar.gz";
+        sha256 = "0mqxa2s194nif7x4fjn1p5gd9i3bakr8nv27gf8x1g5nmi8q9pmp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_compare/ppx_compare.v0.14.0";
+        hash = "sha256:1ndfsgazb7yg5q3aqzcrnr914sf615bsh4z4q202bdvpf0fqj31k";
+      };
+    };
+    ppx_custom_printf = 
+    {
+      pname = "ppx_custom_printf";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_custom_printf/archive/v0.14.1.tar.gz";
+        sha256 = "0kzbckbvhfn3s9an1hq01qd5iac7wgirw182ablpqxc6r3dmijrl";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_custom_printf/ppx_custom_printf.v0.14.1";
+        hash = "sha256:1karjqaa17ai6v4y7wb2zwfpscyirmb4ixdr3lw6i83icklsgmdw";
+      };
+    };
+    ppx_derivers = 
+    {
+      pname = "ppx_derivers";
+      version = "1.2.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-ppx/ppx_derivers/archive/1.2.1.tar.gz";
+        sha256 = "159vqy616ni18mn0dlv8c2y4h7mb4hahwjn53yrr59yyhzhmwndn";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_derivers/ppx_derivers.1.2.1";
+        hash = "sha256:1hj1ina0n7pgz16mrvijczapw75pd0hif0i18dpw7d1fyg2qr8py";
+      };
+    };
+    ppx_enumerate = 
+    {
+      pname = "ppx_enumerate";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_enumerate-v0.14.0.tar.gz";
+        sha256 = "1ij6sffgqhnjwnj9brhrrw1c6xgxlh0s6r17x1qkgnyrc73gfsz8";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_enumerate/ppx_enumerate.v0.14.0";
+        hash = "sha256:0lgnrpq1vmb44367y7mdr7jw1yqmy08fi6phgq8pch3a47fdk2rm";
+      };
+    };
+    ppx_expect = 
+    {
+      pname = "ppx_expect";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_expect/archive/v0.14.2.tar.gz";
+        sha256 = "1gcjlya6knnsrl60sd3vlgp7arj39xm5fjjfk5sick4z66agm2n5";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio re ppxlib ppx_inline_test ppx_here ocaml
+        dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_expect/ppx_expect.v0.14.2";
+        hash = "sha256:14hnawvs9fc87kghg00zj0p1p21f22gdy1767l2nwb4ihl3h133b";
+      };
+    };
+    ppx_fields_conv = 
+    {
+      pname = "ppx_fields_conv";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_fields_conv/archive/v0.14.2.tar.gz";
+        sha256 = "0r7d51j54r1za6bwqsmhmhhfab8n10zyk5zznhkm91f20dx9ddip";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml fieldslib dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_fields_conv/ppx_fields_conv.v0.14.2";
+        hash = "sha256:0332mrn1xk3423rm4hk5lif9igrj3339xyfd6464wcbkpakivfba";
+      };
+    };
+    ppx_fixed_literal = 
+    {
+      pname = "ppx_fixed_literal";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_fixed_literal-v0.14.0.tar.gz";
+        sha256 = "0w0a06143mhmczbpr0lfb66r6im7075gck4p0idbcari63sximqj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_fixed_literal/ppx_fixed_literal.v0.14.0";
+        hash = "sha256:13wng3z0x3fx6l4vym8rddc0yniplim94gn5x8bcfkjd2yhxd88s";
+      };
+    };
+    ppx_hash = 
+    {
+      pname = "ppx_hash";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_hash-v0.14.0.tar.gz";
+        sha256 = "0x4wgdvhgd8a49bzari52jpkykxpv6ncgp5ncda3xgg0a9r49s8n";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_compare ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_hash/ppx_hash.v0.14.0";
+        hash = "sha256:0zcnsd0724w6kpx4w1i3nbfrvffhnqjn3rinddgqjndx5pvghrlc";
+      };
+    };
+    ppx_here = 
+    {
+      pname = "ppx_here";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_here-v0.14.0.tar.gz";
+        sha256 = "0b444djy68v6ji0ypwv5l02pkl151qzrgg96lyhl8dxfrzvj1zkj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_here/ppx_here.v0.14.0";
+        hash = "sha256:0f7p619ymqm27iclcx3cbyyn1k0mccw9vsa0l88m1jk3kjgjbmzz";
+      };
+    };
+    ppx_inline_test = 
+    {
+      pname = "ppx_inline_test";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_inline_test/archive/v0.14.1.tar.gz";
+        sha256 = "0qzvm8rg07annl8zpqlhzx1z8ahrrf02r1brd43ykqas5sww3rfp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) time_now ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_inline_test/ppx_inline_test.v0.14.1";
+        hash = "sha256:1vwg8bgw093ia075n7vh0kl82sjd5r9yk27s45ljzz9cmfqrr4sa";
+      };
+    };
+    ppx_jane = 
+    {
+      pname = "ppx_jane";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_jane-v0.14.0.tar.gz";
+        sha256 = "18js98xdqf8d54sjn1gccjkwbv2p56qy7bhvjgk94pr3fipfz0v7";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_variants_conv ppx_typerep_conv
+        ppx_string ppx_stable ppx_sexp_value ppx_sexp_message ppx_pipebang
+        ppx_optional ppx_optcomp ppx_module_timer ppx_let ppx_inline_test
+        ppx_here ppx_fixed_literal ppx_fields_conv ppx_expect
+        ppx_custom_printf ppx_bin_prot ppx_bench ppx_base ppx_assert ocaml
+        dune base_quickcheck;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_jane/ppx_jane.v0.14.0";
+        hash = "sha256:1jqzfdg3rbb96mgw0cpbsmr1y06whhqys6a4rkfdih6z4n5cm4ns";
+      };
+    };
+    ppx_js_style = 
+    {
+      pname = "ppx_js_style";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_js_style/archive/refs/tags/v0.14.1.tar.gz";
+        sha256 = "1nq4rj659f34dc28pj7ir2szqbpky4nzs9qfw0am6sf36jwispiw";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib octavius ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_js_style/ppx_js_style.v0.14.1";
+        hash = "sha256:05bc07ghvfd4d85inf1qvpqxphvcg7mgf8fn9ycib6fdmxdkkamq";
+      };
+    };
+    ppx_let = 
+    {
+      pname = "ppx_let";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_let-v0.14.0.tar.gz";
+        sha256 = "1qcrnd86pbr1di5m6z4ps4p15qawwa02jxwz3xfd82hdbjmdwf1s";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_let/ppx_let.v0.14.0";
+        hash = "sha256:1n3ayvvmiwmv5jnyjl8nr510dblijwx9g2r39hl5xxgr57d4c7f7";
+      };
+    };
+    ppx_module_timer = 
+    {
+      pname = "ppx_module_timer";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_module_timer-v0.14.0.tar.gz";
+        sha256 = "04a7vzk4s3jn6wj94q0hn8kd9vxlzkpcq5ifpvz3bdfgmypjks5z";
+      };
+      opamInputs = 
+      {
+        inherit (selection) time_now stdio ppxlib ppx_base ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_module_timer/ppx_module_timer.v0.14.0";
+        hash = "sha256:18q8zyppvl9wskx5flhcfmkznzihfs3kk3c38n0kdh1ngg6c1prr";
+      };
+    };
+    ppx_optcomp = 
+    {
+      pname = "ppx_optcomp";
+      version = "v0.14.3";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_optcomp/archive/v0.14.3.tar.gz";
+        sha256 = "0bxzh0pm3zdiadrd37jjzp7zm2qn28mx25ahk0shgfb73vya809n";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_optcomp/ppx_optcomp.v0.14.3";
+        hash = "sha256:0xh7m3hsm7vrhzmd86n3irhydp9lyr23ax9mg1khq2jhcbyqqvy0";
+      };
+    };
+    ppx_optional = 
+    {
+      pname = "ppx_optional";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_optional-v0.14.0.tar.gz";
+        sha256 = "1hh6ivlp1qpvyn8l0vhrahkkcp3scf7km254sgplprmk10wnyidz";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_optional/ppx_optional.v0.14.0";
+        hash = "sha256:0jg35ql4vwzh27hv2vn52hilfb2cpdl91wiaj0r6nh9s6iwy8dzf";
+      };
+    };
+    ppx_pipebang = 
+    {
+      pname = "ppx_pipebang";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_pipebang-v0.14.0.tar.gz";
+        sha256 = "19afbbvy72i1347prvkpy3ms75xnk7kl2hn83h40p6yh27100hky";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_pipebang/ppx_pipebang.v0.14.0";
+        hash = "sha256:1rklw915zv3apij5icp19337aza8di19sp86qp0w6lwimmdvx7dn";
+      };
+    };
+    ppx_sexp_conv = 
+    {
+      pname = "ppx_sexp_conv";
+      version = "v0.14.3";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_sexp_conv/archive/v0.14.3.tar.gz";
+        sha256 = "0fbnkhsd6yphc49pa21nlmbik99n7qkaz8l9paq96v012ipg9h9g";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_sexp_conv/ppx_sexp_conv.v0.14.3";
+        hash = "sha256:03c4ar76g1sz2y35a9jbffw957i17ixwd7ky8cg5ss7m7jl7x1fs";
+      };
+    };
+    ppx_sexp_message = 
+    {
+      pname = "ppx_sexp_message";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_sexp_message/archive/v0.14.1.tar.gz";
+        sha256 = "06d1cx8nh6chgx09lqjgsagc02lfsvv18fydrviqjvydx52m2qjf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_here ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_sexp_message/ppx_sexp_message.v0.14.1";
+        hash = "sha256:0djv8npvc7lx1d20f3ln3s3hffh729fpyyj156fpylkqnr9lcfv7";
+      };
+    };
+    ppx_sexp_value = 
+    {
+      pname = "ppx_sexp_value";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_sexp_value-v0.14.0.tar.gz";
+        sha256 = "0yc6i1yx9mb8pwjkswy09aqg5kz1hgrpjyniq2v6whfjvxl1qrkj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_here ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_sexp_value/ppx_sexp_value.v0.14.0";
+        hash = "sha256:0wqj7nr9nvyss3qjf5jcbijjqkrah2ib8ypfp4hxw00vmyfvyrps";
+      };
+    };
+    ppx_stable = 
+    {
+      pname = "ppx_stable";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_stable/archive/v0.14.1.tar.gz";
+        sha256 = "1dw8ilrvi5lssxnbflnzskmyi3k93ij2kbyz49y93agv0b8dsq01";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_stable/ppx_stable.v0.14.1";
+        hash = "sha256:1b2kvif9jc2wj99ciaz6876myn05qbk3a7gn40msnpmd9prgg1lc";
+      };
+    };
+    ppx_string = 
+    {
+      pname = "ppx_string";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_string/archive/v0.14.1.tar.gz";
+        sha256 = "1a8f7bplbxvwm4lh0m57j89jkwkxfm9r5ndcvvlj5v6py8pv69wj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio ppxlib ppx_base ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_string/ppx_string.v0.14.1";
+        hash = "sha256:0adczy40rfpif3jwz2vrhf8kphzilvgffws2si9ypzs264ipjvg8";
+      };
+    };
+    ppx_typerep_conv = 
+    {
+      pname = "ppx_typerep_conv";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_typerep_conv/archive/v0.14.2.tar.gz";
+        sha256 = "1g1sb3prscpa7jwnk08f50idcgyiiv0b9amkl0kymj5cghkdqw0n";
+      };
+      opamInputs = 
+      {
+        inherit (selection) typerep ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_typerep_conv/ppx_typerep_conv.v0.14.2";
+        hash = "sha256:13fsnz1ndp973s265alzn2l8r1s5bwyica864xgl247yp77f8yy2";
+      };
+    };
+    ppx_variants_conv = 
+    {
+      pname = "ppx_variants_conv";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_variants_conv/archive/v0.14.2.tar.gz";
+        sha256 = "06d63vi2ijzqa3wqnywwqywldq72karss39zi47d544y10rq4rid";
+      };
+      opamInputs = 
+      {
+        inherit (selection) variantslib ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_variants_conv/ppx_variants_conv.v0.14.2";
+        hash = "sha256:0x7xyzzdp9gpx3j32nkh8n1baw8831ppa40c5s4lb4f5gpzjg9m9";
+      };
+    };
+    ppxlib = 
+    {
+      pname = "ppxlib";
+      version = "0.24.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-ppx/ppxlib/releases/download/0.24.0/ppxlib-0.24.0.tbz";
+        sha256 = "1j4hg8gc8mkw64gvjghig1179ih90yki54hf8qxmn3yd5ry04rkp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdlib-shims sexplib0 ppx_derivers
+        ocaml-compiler-libs ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppxlib/ppxlib.0.24.0";
+        hash = "sha256:0yjsgdkfkbwyjj3yihrqnxlpagrbcr1gln7bxfmx96y3xa4fs8jv";
+      };
+    };
+    protocol_version_header = 
+    {
+      pname = "protocol_version_header";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/protocol_version_header-v0.14.0.tar.gz";
+        sha256 = "033xdykhlnpywh0bk6z5dzb5s8gf8h694pgdvnr1l50906vr7np8";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/protocol_version_header/protocol_version_header.v0.14.0";
+        hash = "sha256:1iym5ar75fsw54g94nn8qdzxabspb4xq7gzjs8nz2w15aaln89j0";
+      };
+    };
+    re = 
+    {
+      pname = "re";
+      version = "1.10.3";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/ocaml-re/releases/download/1.10.3/re-1.10.3.tbz";
+        sha256 = "1fqfg609996bgxr14yyfxhvl6hm9c1j0mm2xjdjigqrzgyb4crc4";
+      };
+      opamInputs = {
+                     inherit (selection) seq ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/re/re.1.10.3";
+        hash = "sha256:1f2xgscc07g800ia8z43i1p377dj2fjdrpzsqgzvw1dnplwnklya";
+      };
+    };
+    result = 
+    {
+      pname = "result";
+      version = "1.5";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/result/releases/download/1.5/result-1.5.tbz";
+        sha256 = "0cpfp35fdwnv3p30a06wd0py3805qxmq3jmcynjc3x2qhlimwfkw";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/result/result.1.5";
+        hash = "sha256:0ybmvlisfz5swvbcq855czz1ysv9zxmb79f1m0x8284hczmfm98f";
+      };
+    };
+    seq = 
+    {
+      pname = "seq";
+      version = "base";
+      src = null;
+      opamInputs = {
+                     inherit (selection) ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/seq/seq.base";
+        hash = "sha256:1vm8mk6zm2q3fwnkprl6jib048zr4ysldw0bl74x6wwbxj0vx6k9";
+      };
+    };
+    sexplib = 
+    {
+      pname = "sexplib";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/sexplib-v0.14.0.tar.gz";
+        sha256 = "12rlnc6fcrjfdn3gs2agi418sj54ighhs6dfll37zcv7mgywblm2";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 parsexp ocaml num dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/sexplib/sexplib.v0.14.0";
+        hash = "sha256:1nlzjkx60d4z09b15nq35ivzl6akk3svq7nl4vv5swhsmj8gvpl4";
+      };
+    };
+    sexplib0 = 
+    {
+      pname = "sexplib0";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/sexplib0-v0.14.0.tar.gz";
+        sha256 = "0adrc0r1vvvr41dcpj8jwkzh1dfgqf0mks9xlnnskqfm3a51iavg";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/sexplib0/sexplib0.v0.14.0";
+        hash = "sha256:0k9vkjbiibja48c0yayal7xwyik3h3c3v4dwd3j7jbmras63ig2c";
+      };
+    };
+    spawn = 
+    {
+      pname = "spawn";
+      version = "v0.15.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/spawn/archive/v0.15.0.tar.gz";
+        sha256 = "1isppdyahdcdv8agw1w1l3hyl6kwsbcspjw2h5rlrxn71ajv43ri";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/spawn/spawn.v0.15.0";
+        hash = "sha256:1zfg8d644i2pdq90jwblpi0y8k7xim4xb8i11czpv1qjw2p0s1y1";
+      };
+    };
+    splittable_random = 
+    {
+      pname = "splittable_random";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/splittable_random-v0.14.0.tar.gz";
+        sha256 = "185rpmdnrzs80br138pnjbx9hfp1046zvj1ap0brq1sxdwzak6lf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_sexp_message ppx_inline_test ppx_bench
+        ppx_assert ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/splittable_random/splittable_random.v0.14.0";
+        hash = "sha256:14s1ka5p5af599ira53kygzny65ls49vkxw3xk9ia5xavp7gv4bp";
+      };
+    };
+    stdio = 
+    {
+      pname = "stdio";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/stdio-v0.14.0.tar.gz";
+        sha256 = "1hj5hraprqy2i90a690l11yjszvb99j818q3d684ryx6p2lddk0l";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/stdio/stdio.v0.14.0";
+        hash = "sha256:19hlf6bgx1avq4ifwji2rj2f2j26v3nf8ywjnwh2m3dpvfqc4pvk";
+      };
+    };
+    stdlib-shims = 
+    {
+      pname = "stdlib-shims";
+      version = "0.3.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/stdlib-shims/releases/download/0.3.0/stdlib-shims-0.3.0.tbz";
+        sha256 = "0jnqsv6pqp5b5g7lcjwgd75zqqvcwcl5a32zi03zg1kvj79p5gxs";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/stdlib-shims/stdlib-shims.0.3.0";
+        hash = "sha256:19g9dnaxyh2ajz6pdczdsqzzvsmfrxwx6f613inkr31jw5hrqkiz";
+      };
+    };
+    textutils = 
+    {
+      pname = "textutils";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/textutils-v0.14.0.tar.gz";
+        sha256 = "1ss956gfk2pch3nsqis4x7z79j2d6q002bf8z8xw9z2r64wzi8hl";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel core;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/textutils/textutils.v0.14.0";
+        hash = "sha256:09ikh4xmy7ghzvz8m1p790jbhi04akarlaxqaywjl1f1qbdrhpnk";
+      };
+    };
+    time_now = 
+    {
+      pname = "time_now";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/time_now-v0.14.0.tar.gz";
+        sha256 = "0hkn2jw4dz5gflnsblskl5wp6z7zbrahwjmaxmsskfviwjg82cqh";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_optcomp ppx_base ocaml jst-config
+        jane-street-headers dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/time_now/time_now.v0.14.0";
+        hash = "sha256:1s8bqbks0cjw4x68nn5xlkykn3bcqh2rmrx6hgs53dalkiqv7ry0";
+      };
+    };
+    timezone = 
+    {
+      pname = "timezone";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/timezone-v0.14.0.tar.gz";
+        sha256 = "095xni0szjqqax2r9zh9820l72ixfga2pl0njnarp3795vkw0rdp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/timezone/timezone.v0.14.0";
+        hash = "sha256:1508a5cygb5p4n3kknx8dsrndf9x47fsq232gz4hr9pm8ipriixz";
+      };
+    };
+    topkg = 
+    {
+      pname = "topkg";
+      version = "1.0.4";
+      src = pkgs.fetchurl 
+      {
+        url = "https://erratique.ch/software/topkg/releases/topkg-1.0.4.tbz";
+        sha256 = "1kzw5cxkizcvh4rgzwgpjlj9hfxfk6yr686bxx6wrbsfs8as371k";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocamlfind ocamlbuild ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/topkg/topkg.1.0.4";
+        hash = "sha256:0gvngd4nayhhw02gcsljvmx6jkjpv9m3mqwpgimcfq04h0cf4knb";
+      };
+    };
+    typerep = 
+    {
+      pname = "typerep";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/typerep-v0.14.0.tar.gz";
+        sha256 = "0rmp5jsjg6sgn5yx0pcvch0phs7nak2fg1d48g5sjcyyyj8n1279";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/typerep/typerep.v0.14.0";
+        hash = "sha256:1hhgz8nrarcmbrnknah05wlz3yf1sq4j4mjgjajmbjnls26dkyfa";
+      };
+    };
+    uchar = 
+    {
+      pname = "uchar";
+      version = "0.0.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/uchar/releases/download/v0.0.2/uchar-0.0.2.tbz";
+        sha256 = "1w2saw7zanf9m9ffvz2lvcxvlm118pws2x1wym526xmydhqpyfa7";
+      };
+      opamInputs = {
+                     inherit (selection) ocamlbuild ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/uchar/uchar.0.0.2";
+        hash = "sha256:17sfpyj5a1z3knnjvnfa5vql6cj2x9pzgzk8w4jrvd2zii2bwpcl";
+      };
+    };
+    uutf = 
+    {
+      pname = "uutf";
+      version = "1.0.2";
+      src = pkgs.fetchurl 
+      {
+        url = "http://erratique.ch/software/uutf/releases/uutf-1.0.2.tbz";
+        sha256 = "1nx1rly3qj23jzn9yk3x6fwqimcxjd84kv5859vvhdg56psq26p6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) uchar topkg ocamlfind ocamlbuild
+        ocaml;
+        cmdliner = selection.cmdliner or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/uutf/uutf.1.0.2";
+        hash = "sha256:1j4hkk196lg1dsnf6jb1n8y3na606lkfb5vlr0gjb53qc7pdh6cy";
+      };
+    };
+    variantslib = 
+    {
+      pname = "variantslib";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/variantslib-v0.14.0.tar.gz";
+        sha256 = "11zp27gh282dx9ifbhcp6i7fkc97fvk8amaj58mf1g1hwklc0lm3";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/variantslib/variantslib.v0.14.0";
+        hash = "sha256:1g0z5w2wgsj59vrz7mdzjxdg0vxhck0q8yvzhvag77xzw85r5kjs";
+      };
+    };
+  };
+}
+
diff --git a/nix/opam-selection_4_12.nix b/nix/opam-selection_4_12.nix
new file mode 100644
index 00000000..7accee14
--- /dev/null
+++ b/nix/opam-selection_4_12.nix
@@ -0,0 +1,1822 @@
+### This file is generated by opam2nix.
+
+self:
+let
+    lib = self.lib;
+    pkgs = self.pkgs;
+    selection = self.selection;
+    repoPath = self.repoPath;
+    repos = 
+    {
+      opam-repository = 
+      rec {
+        fetch = 
+        {
+          owner = "ocaml";
+          repo = "opam-repository";
+          rev = "448eb8eb91b9e5db70daeb6fff52877ff6d72791";
+          sha256 = "1653jc4886z7spwkbfpblrjjwsfbwd0xzggrmrxfjps5a1zwi88q";
+        };
+        src = (pkgs.fetchFromGitHub) fetch;
+      };
+    };
+in
+{
+  format-version = 4;
+  inherit repos;
+  ocaml-version = "4.12.0";
+  selection = 
+  {
+    alcotest = 
+    {
+      pname = "alcotest";
+      version = "1.5.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/mirage/alcotest/releases/download/1.5.0/alcotest-js-1.5.0.tbz";
+        sha256 = "0v4ghia378g3l53r61fj98ljha0qxl82xp26y9frjy1dw03ija2l";
+      };
+      opamInputs = 
+      {
+        inherit (selection) uutf stdlib-shims re ocaml-syntax-shims ocaml fmt
+        dune cmdliner astring;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/alcotest/alcotest.1.5.0";
+        hash = "sha256:0rj1wwjawpls9y4dbq2fkw5pa2484vw5jdrw4w54ypafy8qalhk0";
+      };
+    };
+    angstrom = 
+    {
+      pname = "angstrom";
+      version = "0.15.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/angstrom/archive/0.15.0.tar.gz";
+        sha256 = "01cjjal8vjsm225v9y0q6ixam8k5f821rcr6yix6i9nzs84aq6gi";
+      };
+      opamInputs = 
+      {
+        inherit (selection) result ocaml-syntax-shims ocaml dune bigstringaf;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/angstrom/angstrom.0.15.0";
+        hash = "sha256:07ryik3g3hz79hnfdwxdh2jsw3cmbgygjs7mjdw07p927wkd83k9";
+      };
+    };
+    astring = 
+    {
+      pname = "astring";
+      version = "0.8.5";
+      src = pkgs.fetchurl 
+      {
+        url = "https://erratique.ch/software/astring/releases/astring-0.8.5.tbz";
+        sha256 = "1ykhg9gd3iy7zsgyiy2p9b1wkpqg9irw5pvcqs3sphq71iir4ml6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) topkg ocamlfind ocamlbuild ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/astring/astring.0.8.5";
+        hash = "sha256:1djnad9sq12idlakj069xvwm2nn7wqm137pqbxxai5frkgi08x74";
+      };
+    };
+    async = 
+    {
+      pname = "async";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async-v0.14.0.tar.gz";
+        sha256 = "0r6w2df5wn4xjhkhscnxrriwg19qwlxcss3srj4j5fg33jqbgwkl";
+      };
+      opamInputs = 
+      {
+        inherit (selection) textutils ppx_jane ocaml dune core_kernel core
+        async_unix async_rpc_kernel async_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async/async.v0.14.0";
+        hash = "sha256:085dsrvxlk1qmszhhi45h7z6w85fz7ik468ylx71ap3977cpayha";
+      };
+    };
+    async_kernel = 
+    {
+      pname = "async_kernel";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async_kernel-v0.14.0.tar.gz";
+        sha256 = "13k0dsbvw69jl6ckqrvigdvjffcqy778nish3370kl9lkmp0c49m";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async_kernel/async_kernel.v0.14.0";
+        hash = "sha256:185cp75vc3sgirs34xxmy5ggnvjpbj8sxxnl3p5n1v2kldf7n28j";
+      };
+    };
+    async_rpc_kernel = 
+    {
+      pname = "async_rpc_kernel";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async_rpc_kernel-v0.14.0.tar.gz";
+        sha256 = "1xrrpmhwhav3prr382q088h8sn7dax2s58hkwcv4ilcwx4zbmyk8";
+      };
+      opamInputs = 
+      {
+        inherit (selection) protocol_version_header ppx_jane ocaml dune
+        core_kernel async_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async_rpc_kernel/async_rpc_kernel.v0.14.0";
+        hash = "sha256:1l3wa564cqhjc47cwqf3a51d44cgzijmvrhjm0z0jakm6sj0rmww";
+      };
+    };
+    async_unix = 
+    {
+      pname = "async_unix";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async_unix-v0.14.0.tar.gz";
+        sha256 = "1f9jv97xs3lgw4n7p7b95nixldh47gpbh6shcnsf0ccjxgnwx5xf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel core async_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async_unix/async_unix.v0.14.0";
+        hash = "sha256:095m4yxgvxg2cwqa2jas6lc16w1rllzwg7v29kgbbgwlg3l91lv7";
+      };
+    };
+    base = 
+    {
+      pname = "base";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/base/archive/v0.14.2.tar.gz";
+        sha256 = "095zbz0bqrmhgw62jyhb51kqp89kph1cfcpr5ww94slr5rldpj7i";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 ocaml dune-configurator dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base/base.v0.14.2";
+        hash = "sha256:004ypm5lr9mp7glgfggi47x8h644f9z7xrx5gahsx1l82b566frv";
+      };
+    };
+    base-bytes = 
+    {
+      pname = "base-bytes";
+      version = "base";
+      src = null;
+      opamInputs = {
+                     inherit (selection) ocamlfind ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base-bytes/base-bytes.base";
+        hash = "sha256:0a68lmbf68jgm1i3b59j2sc3ha9yhv4678f9mfwwvczw88prq7l3";
+      };
+    };
+    base-threads = 
+    {
+      pname = "base-threads";
+      version = "base";
+      src = null;
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base-threads/base-threads.base";
+        hash = "sha256:1c4bpyh61ampjgk5yh3inrgcpf1z1xv0pshn54ycmpn4dyzv0p2x";
+      };
+    };
+    base-unix = 
+    {
+      pname = "base-unix";
+      version = "base";
+      src = null;
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base-unix/base-unix.base";
+        hash = "sha256:0mpsvb7684g723ylngryh15aqxg3blb7hgmq2fsqjyppr36iyzwg";
+      };
+    };
+    base_bigstring = 
+    {
+      pname = "base_bigstring";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/base_bigstring-v0.14.0.tar.gz";
+        sha256 = "1fhldk58w56ixkin763kpic512xvkkf9b4mrnjfsbm8in75kzndq";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base_bigstring/base_bigstring.v0.14.0";
+        hash = "sha256:0yn51npq4fwi9nllfhq2r3kkb17pg3igvvjgblac1g3v0nmhj6c4";
+      };
+    };
+    base_quickcheck = 
+    {
+      pname = "base_quickcheck";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/base_quickcheck/archive/v0.14.1.tar.gz";
+        sha256 = "0n5h0ysn593awvz4crkvzf5r800hd1c55bx9mm9vbqs906zii6mn";
+      };
+      opamInputs = 
+      {
+        inherit (selection) splittable_random ppxlib ppx_sexp_value
+        ppx_sexp_message ppx_let ppx_fields_conv ppx_base ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base_quickcheck/base_quickcheck.v0.14.1";
+        hash = "sha256:0lxxagkyg1jh0x7bbps1972bid51a82m1h2x3nyz342dnsy4k6h1";
+      };
+    };
+    bigarray-compat = 
+    {
+      pname = "bigarray-compat";
+      version = "1.0.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/mirage/bigarray-compat/archive/v1.0.0.tar.gz";
+        sha256 = "1bpmmnxb1yx72aqlbdaqfl18rgz1cq9cf6cqvnfl88mz5dfr4x0d";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/bigarray-compat/bigarray-compat.1.0.0";
+        hash = "sha256:0mcg8csmd60ph17vam1s8xjsl9kp6k77i3mnkbxy0jvkn49m4a0k";
+      };
+    };
+    bigstringaf = 
+    {
+      pname = "bigstringaf";
+      version = "0.8.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/bigstringaf/archive/0.8.0.tar.gz";
+        sha256 = "06w66xnqgv8r92x50b3q6xrymry6fviyj572dw7y76cqdzfph18z";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune conf-pkg-config
+        bigarray-compat;
+        ocaml-freestanding = selection.ocaml-freestanding or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/bigstringaf/bigstringaf.0.8.0";
+        hash = "sha256:0q3v7v83pj1rf7qzqj5silkx0s8sjpkwjzkvnmnqkyp4aljqnlnb";
+      };
+    };
+    bin_prot = 
+    {
+      pname = "bin_prot";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/bin_prot-v0.14.0.tar.gz";
+        sha256 = "1f1ng6cixi3ci0nb765yfzqk9b3s752hy1i3702kh59gni1psycp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_variants_conv ppx_sexp_conv ppx_optcomp
+        ppx_fields_conv ppx_custom_printf ppx_compare ocaml dune
+        base;
+        mirage-xen-ocaml = selection.mirage-xen-ocaml or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/bin_prot/bin_prot.v0.14.0";
+        hash = "sha256:17ylwhh1kv9klavfag20n4g3175i7nmljbdj12z9yiqm4da3r4rk";
+      };
+    };
+    cmdliner = 
+    {
+      pname = "cmdliner";
+      version = "1.0.4";
+      src = pkgs.fetchurl 
+      {
+        url = "http://erratique.ch/software/cmdliner/releases/cmdliner-1.0.4.tbz";
+        sha256 = "1h04q0zkasd0mw64ggh4y58lgzkhg6yhzy60lab8k8zq9ba96ajw";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/cmdliner/cmdliner.1.0.4";
+        hash = "sha256:05qlm4yp6124w2z10dpdchldfrmgmcr6h31rnxp8qs8mk0xzx48z";
+      };
+    };
+    conf-pkg-config = 
+    {
+      pname = "conf-pkg-config";
+      version = "2";
+      src = null;
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/conf-pkg-config/conf-pkg-config.2";
+        hash = "sha256:1rli6809glz5g9xwp4wsjidc39za4n58xcpkamy6fymfnqha225n";
+      };
+      buildInputs = [ (pkgs.pkgconfig) ];
+    };
+    core = 
+    {
+      pname = "core";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/core/archive/v0.14.1.tar.gz";
+        sha256 = "1862zsk85i00vsv2chgb156b1chp8f7p508hsz6sadjx6h98q5cc";
+      };
+      opamInputs = 
+      {
+        inherit (selection) timezone spawn sexplib ppx_jane ocaml jst-config
+        dune core_kernel base-threads;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/core/core.v0.14.1";
+        hash = "sha256:13hkxn24szh9j0xl6m65k9cg8blqh44yb0nz9m5wrfbyfn8zd1hd";
+      };
+      buildInputs = [ (pkgs.linux-headers or null) ];
+    };
+    core_kernel = 
+    {
+      pname = "core_kernel";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/core_kernel/archive/v0.14.2.tar.gz";
+        sha256 = "0jyf08i9wzg3yf32f158i6n9gm751bk8zj7xqx79jnnkchwkbxb6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) variantslib typerep time_now stdio
+        splittable_random sexplib ppx_sexp_message ppx_sexp_conv ppx_optcomp
+        ppx_jane ppx_inline_test ppx_hash ppx_base ppx_assert ocaml
+        jst-config jane-street-headers fieldslib dune bin_prot
+        base_quickcheck base_bigstring base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/core_kernel/core_kernel.v0.14.2";
+        hash = "sha256:09c7k6m1vm8jhqfivn8w663v362qwjf6cb5xlzijd0sjgh1dwai5";
+      };
+    };
+    cppo = 
+    {
+      pname = "cppo";
+      version = "1.6.8";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-community/cppo/archive/v1.6.8.tar.gz";
+        sha256 = "0lxy4xkkkwgs1cj6d9lyzsqi9f6fc9r6cir5imi7yjqrpd86s1by";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune base-unix;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/cppo/cppo.1.6.8";
+        hash = "sha256:0pzd8irqkkkpfgw8nq9d21z9rj5m3qlzixyb7ybfy4b1fwh3n8bp";
+      };
+    };
+    csexp = 
+    {
+      pname = "csexp";
+      version = "1.5.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-dune/csexp/releases/download/1.5.1/csexp-1.5.1.tbz";
+        sha256 = "00mc19f89pxpmjl62862ya5kjcfrl8rjzvs00j05h2m9bw3f81fn";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/csexp/csexp.1.5.1";
+        hash = "sha256:01lc95kz13gpki4xazyh6n20kv1g9inyb5myv240wl2n9v50z8fl";
+      };
+    };
+    dune = 
+    {
+      pname = "dune";
+      version = "2.9.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/dune/releases/download/2.9.2/dune-site-2.9.2.tbz";
+        sha256 = "0ivl5r9diky8r1rfka7427kc3lh168mrz0ywdxgv8y5rgx8crrxq";
+      };
+      opamInputs = 
+      {
+        inherit (selection) base-unix
+        base-threads;
+        ocamlfind-secondary = selection.ocamlfind-secondary or null;
+        ocaml = selection.ocaml or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/dune/dune.2.9.2";
+        hash = "sha256:0qzzy2kn29ww9ryl2fvhkph9lmc112yr86xn8r8s9rbaz2zfkm6x";
+      };
+    };
+    dune-configurator = 
+    {
+      pname = "dune-configurator";
+      version = "2.9.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/dune/releases/download/2.9.1/dune-2.9.1.tbz";
+        sha256 = "09lzq04b642iy0ljp59p32lgk3q8iphjh8fkdp69q29l5frgwx5k";
+      };
+      opamInputs = 
+      {
+        inherit (selection) result ocaml dune csexp;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/dune-configurator/dune-configurator.2.9.1";
+        hash = "sha256:1aik9w82r8vbb9fsfphpb0vam68s19ggkxprnqr99ygyalp2b71j";
+      };
+    };
+    faraday = 
+    {
+      pname = "faraday";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune bigstringaf;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday/faraday.0.8.1";
+        hash = "sha256:1gk9zcifglbfnkjhndd96xf6bfp5ldmrpvvy3daidfd07l56vr96";
+      };
+    };
+    faraday-async = 
+    {
+      pname = "faraday-async";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml faraday dune core async;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday-async/faraday-async.0.8.1";
+        hash = "sha256:0vwz2qn0mmv8n4xl1jcjghnj0cfy66yq621mmhd0vgnfqyw4sysm";
+      };
+    };
+    faraday-lwt = 
+    {
+      pname = "faraday-lwt";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml lwt faraday dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday-lwt/faraday-lwt.0.8.1";
+        hash = "sha256:14nrlva43l45wp71rbyk2fb9nk43krqp292wzrlmc8ip19pc8y9p";
+      };
+    };
+    faraday-lwt-unix = 
+    {
+      pname = "faraday-lwt-unix";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml lwt faraday-lwt dune base-unix;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday-lwt-unix/faraday-lwt-unix.0.8.1";
+        hash = "sha256:1zfzrrbfdvw4mbmp5alkv8bmhcsfr5nillb2nj6p49fab347182m";
+      };
+    };
+    fieldslib = 
+    {
+      pname = "fieldslib";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/fieldslib-v0.14.0.tar.gz";
+        sha256 = "10n5y376fb5jgqk9h8vq158rm1b36h9lzh6p11q33h6xgvb1v6n3";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/fieldslib/fieldslib.v0.14.0";
+        hash = "sha256:1gsrbs4x45k4bp1zih9c6db3axhaiy91knac6bk6hpgv9sjalicm";
+      };
+    };
+    fmt = 
+    {
+      pname = "fmt";
+      version = "0.9.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://erratique.ch/software/fmt/releases/fmt-0.9.0.tbz";
+        sha256 = "0q8j2in2473xh7k4hfgnppv9qy77f2ih89yp6yhpbp92ba021yzi";
+      };
+      opamInputs = 
+      {
+        inherit (selection) topkg ocamlfind ocamlbuild
+        ocaml;
+        cmdliner = selection.cmdliner or null;
+        base-unix = selection.base-unix or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/fmt/fmt.0.9.0";
+        hash = "sha256:1czh5i3i4mkf9xfasji3v7n821qmnnandlklh67ali0x87brldny";
+      };
+    };
+    httpaf = 
+    {
+      pname = "httpaf";
+      version = "development";
+      src = self.directSrc "httpaf";
+      opamInputs = 
+      {
+        inherit (selection) result ocaml faraday dune bigstringaf angstrom;
+      };
+      opamSrc = "httpaf.opam";
+    };
+    httpaf-async = 
+    {
+      pname = "httpaf-async";
+      version = "development";
+      src = self.directSrc "httpaf-async";
+      opamInputs = 
+      {
+        inherit (selection) ocaml httpaf faraday-async dune async;
+      };
+      opamSrc = "httpaf-async.opam";
+    };
+    httpaf-lwt-unix = 
+    {
+      pname = "httpaf-lwt-unix";
+      version = "development";
+      src = self.directSrc "httpaf-lwt-unix";
+      opamInputs = 
+      {
+        inherit (selection) ocaml lwt httpaf faraday-lwt-unix dune;
+      };
+      opamSrc = "httpaf-lwt-unix.opam";
+    };
+    jane-street-headers = 
+    {
+      pname = "jane-street-headers";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/jane-street-headers-v0.14.0.tar.gz";
+        sha256 = "028yxb4h3iy025iy89v8653m5brh7flrjshghs4x99pd690pmfs7";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/jane-street-headers/jane-street-headers.v0.14.0";
+        hash = "sha256:1w6zjjmyszk9pax139rkxb3vx0w23w0pfd46bddfyfkxq2rbwsvf";
+      };
+    };
+    jst-config = 
+    {
+      pname = "jst-config";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/jst-config/archive/refs/tags/v0.14.1.tar.gz";
+        sha256 = "0wdjs0lvc5wbggh27cf490jarfibrrb5xxsrigg41m32kjkbijm4";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio ppx_assert ocaml dune-configurator dune
+        base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/jst-config/jst-config.v0.14.1";
+        hash = "sha256:0myym84b9yx4vqa0ml0zf3cx6rms3g5dv704vhf5bpr7jnqz0qcb";
+      };
+    };
+    lwt = 
+    {
+      pname = "lwt";
+      version = "5.5.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocsigen/lwt/archive/refs/tags/5.5.0.tar.gz";
+        sha256 = "15gr6nhhfjyh91v9chvm6j7vnp1hhc60y3plgvcgl5yl5k7xbbj9";
+      };
+      opamInputs = 
+      {
+        inherit (selection) seq result ocplib-endian ocaml mmap
+        dune-configurator dune
+        cppo;
+        ocaml-syntax-shims = selection.ocaml-syntax-shims or null;
+        conf-libev = selection.conf-libev or null;
+        base-unix = selection.base-unix or null;
+        base-threads = selection.base-threads or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/lwt/lwt.5.5.0";
+        hash = "sha256:0iadlycd4q93lsk07k9zaimlysgd38sj6v50dc3cb491vl0icipz";
+      };
+    };
+    mmap = 
+    {
+      pname = "mmap";
+      version = "1.1.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/mirage/mmap/releases/download/v1.1.0/mmap-v1.1.0.tbz";
+        sha256 = "0l6waidal2n8mkdn74avbslvc10sf49f5d889n838z03pra5chsc";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/mmap/mmap.1.1.0";
+        hash = "sha256:1snhaf6mixmmb49gcin5wmbz4bfjz406mip4556lids8ajm22ibh";
+      };
+    };
+    num = 
+    {
+      pname = "num";
+      version = "1.4";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/num/archive/v1.4.tar.gz";
+        sha256 = "090gl27g84r3s2b12vgkz8fp269jqlrhx4lpg7008yviisv8hl01";
+      };
+      opamInputs = {
+                     inherit (selection) ocamlfind ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/num/num.1.4";
+        hash = "sha256:04wb8ww165lsifn36jcrxw5zs87id5kib6rilq6zh6qhzvij88pf";
+      };
+    };
+    ocaml = 
+    {
+      pname = "ocaml";
+      version = "4.12.0";
+      src = null;
+      opamInputs = 
+      {
+        inherit (selection)
+        ocaml-config;
+        ocaml-variants = selection.ocaml-variants or null;
+        ocaml-system = selection.ocaml-system or null;
+        ocaml-base-compiler = selection.ocaml-base-compiler or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml/ocaml.4.12.0";
+        hash = "sha256:038vq14gnl2qzgk4mjr0xif1xln30wk5hbj2icvq3ql6hszyrf9g";
+      };
+    };
+    ocaml-base-compiler = 
+    {
+      pname = "ocaml-base-compiler";
+      version = "4.12.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/ocaml/archive/4.12.0.tar.gz";
+        sha256 = "0i37laikik5vwydw1cwygxd8xq2d6n35l20irgrh691njlwpmh5d";
+      };
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-base-compiler/ocaml-base-compiler.4.12.0";
+        hash = "sha256:12clsv2kmwsfy685kjkjsyv41krfrr04ccpc11xhv6ar0090bsh5";
+      };
+    };
+    ocaml-compiler-libs = 
+    {
+      pname = "ocaml-compiler-libs";
+      version = "v0.12.4";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ocaml-compiler-libs/releases/download/v0.12.4/ocaml-compiler-libs-v0.12.4.tbz";
+        sha256 = "0q3pl20pkx410gw9g4m26qq6dmzi9qan2dqlga6c2ifc6pnckjaf";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-compiler-libs/ocaml-compiler-libs.v0.12.4";
+        hash = "sha256:1blynia10j8vyj559kcvc7ic69zq6qjjn092fcsjzfw6czd8ya2c";
+      };
+    };
+    ocaml-config = 
+    {
+      pname = "ocaml-config";
+      version = "2";
+      src = null;
+      opamInputs = 
+      {
+        ocaml-variants = selection.ocaml-variants or null;
+        ocaml-system = selection.ocaml-system or null;
+        ocaml-base-compiler = selection.ocaml-base-compiler or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-config/ocaml-config.2";
+        hash = "sha256:0h0hgqq9mbywvqygppfdc50gf9ss8a97l4dgsv3hszmzh6gglgrg";
+      };
+    };
+    ocaml-syntax-shims = 
+    {
+      pname = "ocaml-syntax-shims";
+      version = "1.0.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-ppx/ocaml-syntax-shims/releases/download/1.0.0/ocaml-syntax-shims-1.0.0.tbz";
+        sha256 = "1j7848khli4p7j8i2kmnvhdnhcwhy3zgdpf5ds5ic30ax69y3cl9";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-syntax-shims/ocaml-syntax-shims.1.0.0";
+        hash = "sha256:0qnm1db0298yqcn6j9fmb0l4gr5nhcar8plskj39917invyamgd2";
+      };
+    };
+    ocamlbuild = 
+    {
+      pname = "ocamlbuild";
+      version = "0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/ocamlbuild/archive/0.14.0.tar.gz";
+        sha256 = "0y1fskw9rg2y1zgb7whv3v8v4xw04svgxslf3856q2aqd7lrrcl7";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocamlbuild/ocamlbuild.0.14.0";
+        hash = "sha256:1r5qnrcxfypzyvjvb3zd9f66kr5ldxdl3g9rsi3pb6040krqb5w7";
+      };
+    };
+    ocamlfind = 
+    {
+      pname = "ocamlfind";
+      version = "1.9.3";
+      src = pkgs.fetchurl 
+      {
+        url = "http://download.camlcity.org/download/findlib-1.9.3.tar.gz";
+        sha256 = "0hfcwamcvinmww59b5i4yxbf0kxyzkp5qv3d1c7ybn9q52vgq463";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml;
+        graphics = selection.graphics or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocamlfind/ocamlfind.1.9.3";
+        hash = "sha256:1wq1lkw3rpgilprlakznsxxf60mcidn3fzi3vjrgjdrnnp9hvh19";
+      };
+    };
+    ocplib-endian = 
+    {
+      pname = "ocplib-endian";
+      version = "1.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/OCamlPro/ocplib-endian/archive/refs/tags/1.2.tar.gz";
+        sha256 = "085kskr0cxcnv2d62n3jq1r273p7giisy56zfl26mm7amvl79blp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune cppo base-bytes;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocplib-endian/ocplib-endian.1.2";
+        hash = "sha256:1jldvb471gyhkrzwfvqg722l3a8dc37hhhyas66skjzfmqyi2pnh";
+      };
+    };
+    octavius = 
+    {
+      pname = "octavius";
+      version = "1.2.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-doc/octavius/archive/v1.2.2.tar.gz";
+        sha256 = "1bg0fcm7haqxvx5wx2cci0mbbq0gf1vw9fa4kkd6jsriw1611jga";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/octavius/octavius.1.2.2";
+        hash = "sha256:0bagilkanfjyi56hrk9dw43xs6zry9p8n3l55r3d58v5hz2xsbwl";
+      };
+    };
+    parsexp = 
+    {
+      pname = "parsexp";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/parsexp/archive/refs/tags/v0.14.2.tar.gz";
+        sha256 = "0c7jl6sqfawqpvbhci8vyyhgvcyd3lw5lj3jcf5f1p6w1177xqgn";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/parsexp/parsexp.v0.14.2";
+        hash = "sha256:1fqnxdr1pgxmada77hkhyyr7yybpv2f810shnhvhkpw15h58azx1";
+      };
+    };
+    ppx_assert = 
+    {
+      pname = "ppx_assert";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_assert-v0.14.0.tar.gz";
+        sha256 = "1l2rr4jz2q5b35ryn2z146z7m9v6k8krp5gpn8ilib66mnz5zx15";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_here ppx_compare
+        ppx_cold ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_assert/ppx_assert.v0.14.0";
+        hash = "sha256:1ry1bqssjw5lc7h0x2cc7f8rmz807j5l7029lxd4i12vgq91x5km";
+      };
+    };
+    ppx_base = 
+    {
+      pname = "ppx_base";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_base-v0.14.0.tar.gz";
+        sha256 = "0b7a3fmi90jk8paz0g36yzaq670fbnrbi1j8r5ibh9wbcfli7ji6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_js_style ppx_hash
+        ppx_enumerate ppx_compare ppx_cold ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_base/ppx_base.v0.14.0";
+        hash = "sha256:1n66x8xl2n0qbq1g0b1l3nsdqlb3czj5w509riwqdgz11fyrzi25";
+      };
+    };
+    ppx_bench = 
+    {
+      pname = "ppx_bench";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_bench/archive/v0.14.1.tar.gz";
+        sha256 = "1jr3cf4zsk894x64c8ir9ap9l412q35b2605pr7flrlxbm4vkf3f";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_inline_test ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_bench/ppx_bench.v0.14.1";
+        hash = "sha256:0r17lcfhxd14ihbbhqjqjmx26ig4xf62dmc2pblg7flzcf4k64dp";
+      };
+    };
+    ppx_bin_prot = 
+    {
+      pname = "ppx_bin_prot";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_bin_prot-v0.14.0.tar.gz";
+        sha256 = "0wa2jmvm2k88b37pbcafy1mdf5iaip0yxg5dw774sbh28nm08m2s";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_here ocaml dune bin_prot base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_bin_prot/ppx_bin_prot.v0.14.0";
+        hash = "sha256:0rsbhajm4927f1798baalwf3f7f5vs8jy27bxd6rhhybnvqjxyj9";
+      };
+    };
+    ppx_cold = 
+    {
+      pname = "ppx_cold";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_cold-v0.14.0.tar.gz";
+        sha256 = "1madfzhpir9amnxmg530n70vll0jrl59vyp71miji73i6b9sy6n2";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_cold/ppx_cold.v0.14.0";
+        hash = "sha256:0g566vskiblrxr246c3s26rlzxciln518fr4f6d8lid63qgrgnfm";
+      };
+    };
+    ppx_compare = 
+    {
+      pname = "ppx_compare";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_compare-v0.14.0.tar.gz";
+        sha256 = "0mqxa2s194nif7x4fjn1p5gd9i3bakr8nv27gf8x1g5nmi8q9pmp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_compare/ppx_compare.v0.14.0";
+        hash = "sha256:1ndfsgazb7yg5q3aqzcrnr914sf615bsh4z4q202bdvpf0fqj31k";
+      };
+    };
+    ppx_custom_printf = 
+    {
+      pname = "ppx_custom_printf";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_custom_printf/archive/v0.14.1.tar.gz";
+        sha256 = "0kzbckbvhfn3s9an1hq01qd5iac7wgirw182ablpqxc6r3dmijrl";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_custom_printf/ppx_custom_printf.v0.14.1";
+        hash = "sha256:1karjqaa17ai6v4y7wb2zwfpscyirmb4ixdr3lw6i83icklsgmdw";
+      };
+    };
+    ppx_derivers = 
+    {
+      pname = "ppx_derivers";
+      version = "1.2.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-ppx/ppx_derivers/archive/1.2.1.tar.gz";
+        sha256 = "159vqy616ni18mn0dlv8c2y4h7mb4hahwjn53yrr59yyhzhmwndn";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_derivers/ppx_derivers.1.2.1";
+        hash = "sha256:1hj1ina0n7pgz16mrvijczapw75pd0hif0i18dpw7d1fyg2qr8py";
+      };
+    };
+    ppx_enumerate = 
+    {
+      pname = "ppx_enumerate";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_enumerate-v0.14.0.tar.gz";
+        sha256 = "1ij6sffgqhnjwnj9brhrrw1c6xgxlh0s6r17x1qkgnyrc73gfsz8";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_enumerate/ppx_enumerate.v0.14.0";
+        hash = "sha256:0lgnrpq1vmb44367y7mdr7jw1yqmy08fi6phgq8pch3a47fdk2rm";
+      };
+    };
+    ppx_expect = 
+    {
+      pname = "ppx_expect";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_expect/archive/v0.14.2.tar.gz";
+        sha256 = "1gcjlya6knnsrl60sd3vlgp7arj39xm5fjjfk5sick4z66agm2n5";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio re ppxlib ppx_inline_test ppx_here ocaml
+        dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_expect/ppx_expect.v0.14.2";
+        hash = "sha256:14hnawvs9fc87kghg00zj0p1p21f22gdy1767l2nwb4ihl3h133b";
+      };
+    };
+    ppx_fields_conv = 
+    {
+      pname = "ppx_fields_conv";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_fields_conv/archive/v0.14.2.tar.gz";
+        sha256 = "0r7d51j54r1za6bwqsmhmhhfab8n10zyk5zznhkm91f20dx9ddip";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml fieldslib dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_fields_conv/ppx_fields_conv.v0.14.2";
+        hash = "sha256:0332mrn1xk3423rm4hk5lif9igrj3339xyfd6464wcbkpakivfba";
+      };
+    };
+    ppx_fixed_literal = 
+    {
+      pname = "ppx_fixed_literal";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_fixed_literal-v0.14.0.tar.gz";
+        sha256 = "0w0a06143mhmczbpr0lfb66r6im7075gck4p0idbcari63sximqj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_fixed_literal/ppx_fixed_literal.v0.14.0";
+        hash = "sha256:13wng3z0x3fx6l4vym8rddc0yniplim94gn5x8bcfkjd2yhxd88s";
+      };
+    };
+    ppx_hash = 
+    {
+      pname = "ppx_hash";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_hash-v0.14.0.tar.gz";
+        sha256 = "0x4wgdvhgd8a49bzari52jpkykxpv6ncgp5ncda3xgg0a9r49s8n";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_compare ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_hash/ppx_hash.v0.14.0";
+        hash = "sha256:0zcnsd0724w6kpx4w1i3nbfrvffhnqjn3rinddgqjndx5pvghrlc";
+      };
+    };
+    ppx_here = 
+    {
+      pname = "ppx_here";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_here-v0.14.0.tar.gz";
+        sha256 = "0b444djy68v6ji0ypwv5l02pkl151qzrgg96lyhl8dxfrzvj1zkj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_here/ppx_here.v0.14.0";
+        hash = "sha256:0f7p619ymqm27iclcx3cbyyn1k0mccw9vsa0l88m1jk3kjgjbmzz";
+      };
+    };
+    ppx_inline_test = 
+    {
+      pname = "ppx_inline_test";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_inline_test/archive/v0.14.1.tar.gz";
+        sha256 = "0qzvm8rg07annl8zpqlhzx1z8ahrrf02r1brd43ykqas5sww3rfp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) time_now ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_inline_test/ppx_inline_test.v0.14.1";
+        hash = "sha256:1vwg8bgw093ia075n7vh0kl82sjd5r9yk27s45ljzz9cmfqrr4sa";
+      };
+    };
+    ppx_jane = 
+    {
+      pname = "ppx_jane";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_jane-v0.14.0.tar.gz";
+        sha256 = "18js98xdqf8d54sjn1gccjkwbv2p56qy7bhvjgk94pr3fipfz0v7";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_variants_conv ppx_typerep_conv
+        ppx_string ppx_stable ppx_sexp_value ppx_sexp_message ppx_pipebang
+        ppx_optional ppx_optcomp ppx_module_timer ppx_let ppx_inline_test
+        ppx_here ppx_fixed_literal ppx_fields_conv ppx_expect
+        ppx_custom_printf ppx_bin_prot ppx_bench ppx_base ppx_assert ocaml
+        dune base_quickcheck;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_jane/ppx_jane.v0.14.0";
+        hash = "sha256:1jqzfdg3rbb96mgw0cpbsmr1y06whhqys6a4rkfdih6z4n5cm4ns";
+      };
+    };
+    ppx_js_style = 
+    {
+      pname = "ppx_js_style";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_js_style/archive/refs/tags/v0.14.1.tar.gz";
+        sha256 = "1nq4rj659f34dc28pj7ir2szqbpky4nzs9qfw0am6sf36jwispiw";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib octavius ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_js_style/ppx_js_style.v0.14.1";
+        hash = "sha256:05bc07ghvfd4d85inf1qvpqxphvcg7mgf8fn9ycib6fdmxdkkamq";
+      };
+    };
+    ppx_let = 
+    {
+      pname = "ppx_let";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_let-v0.14.0.tar.gz";
+        sha256 = "1qcrnd86pbr1di5m6z4ps4p15qawwa02jxwz3xfd82hdbjmdwf1s";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_let/ppx_let.v0.14.0";
+        hash = "sha256:1n3ayvvmiwmv5jnyjl8nr510dblijwx9g2r39hl5xxgr57d4c7f7";
+      };
+    };
+    ppx_module_timer = 
+    {
+      pname = "ppx_module_timer";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_module_timer-v0.14.0.tar.gz";
+        sha256 = "04a7vzk4s3jn6wj94q0hn8kd9vxlzkpcq5ifpvz3bdfgmypjks5z";
+      };
+      opamInputs = 
+      {
+        inherit (selection) time_now stdio ppxlib ppx_base ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_module_timer/ppx_module_timer.v0.14.0";
+        hash = "sha256:18q8zyppvl9wskx5flhcfmkznzihfs3kk3c38n0kdh1ngg6c1prr";
+      };
+    };
+    ppx_optcomp = 
+    {
+      pname = "ppx_optcomp";
+      version = "v0.14.3";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_optcomp/archive/v0.14.3.tar.gz";
+        sha256 = "0bxzh0pm3zdiadrd37jjzp7zm2qn28mx25ahk0shgfb73vya809n";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_optcomp/ppx_optcomp.v0.14.3";
+        hash = "sha256:0xh7m3hsm7vrhzmd86n3irhydp9lyr23ax9mg1khq2jhcbyqqvy0";
+      };
+    };
+    ppx_optional = 
+    {
+      pname = "ppx_optional";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_optional-v0.14.0.tar.gz";
+        sha256 = "1hh6ivlp1qpvyn8l0vhrahkkcp3scf7km254sgplprmk10wnyidz";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_optional/ppx_optional.v0.14.0";
+        hash = "sha256:0jg35ql4vwzh27hv2vn52hilfb2cpdl91wiaj0r6nh9s6iwy8dzf";
+      };
+    };
+    ppx_pipebang = 
+    {
+      pname = "ppx_pipebang";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_pipebang-v0.14.0.tar.gz";
+        sha256 = "19afbbvy72i1347prvkpy3ms75xnk7kl2hn83h40p6yh27100hky";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_pipebang/ppx_pipebang.v0.14.0";
+        hash = "sha256:1rklw915zv3apij5icp19337aza8di19sp86qp0w6lwimmdvx7dn";
+      };
+    };
+    ppx_sexp_conv = 
+    {
+      pname = "ppx_sexp_conv";
+      version = "v0.14.3";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_sexp_conv/archive/v0.14.3.tar.gz";
+        sha256 = "0fbnkhsd6yphc49pa21nlmbik99n7qkaz8l9paq96v012ipg9h9g";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_sexp_conv/ppx_sexp_conv.v0.14.3";
+        hash = "sha256:03c4ar76g1sz2y35a9jbffw957i17ixwd7ky8cg5ss7m7jl7x1fs";
+      };
+    };
+    ppx_sexp_message = 
+    {
+      pname = "ppx_sexp_message";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_sexp_message/archive/v0.14.1.tar.gz";
+        sha256 = "06d1cx8nh6chgx09lqjgsagc02lfsvv18fydrviqjvydx52m2qjf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_here ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_sexp_message/ppx_sexp_message.v0.14.1";
+        hash = "sha256:0djv8npvc7lx1d20f3ln3s3hffh729fpyyj156fpylkqnr9lcfv7";
+      };
+    };
+    ppx_sexp_value = 
+    {
+      pname = "ppx_sexp_value";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_sexp_value-v0.14.0.tar.gz";
+        sha256 = "0yc6i1yx9mb8pwjkswy09aqg5kz1hgrpjyniq2v6whfjvxl1qrkj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_here ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_sexp_value/ppx_sexp_value.v0.14.0";
+        hash = "sha256:0wqj7nr9nvyss3qjf5jcbijjqkrah2ib8ypfp4hxw00vmyfvyrps";
+      };
+    };
+    ppx_stable = 
+    {
+      pname = "ppx_stable";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_stable/archive/v0.14.1.tar.gz";
+        sha256 = "1dw8ilrvi5lssxnbflnzskmyi3k93ij2kbyz49y93agv0b8dsq01";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_stable/ppx_stable.v0.14.1";
+        hash = "sha256:1b2kvif9jc2wj99ciaz6876myn05qbk3a7gn40msnpmd9prgg1lc";
+      };
+    };
+    ppx_string = 
+    {
+      pname = "ppx_string";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_string/archive/v0.14.1.tar.gz";
+        sha256 = "1a8f7bplbxvwm4lh0m57j89jkwkxfm9r5ndcvvlj5v6py8pv69wj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio ppxlib ppx_base ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_string/ppx_string.v0.14.1";
+        hash = "sha256:0adczy40rfpif3jwz2vrhf8kphzilvgffws2si9ypzs264ipjvg8";
+      };
+    };
+    ppx_typerep_conv = 
+    {
+      pname = "ppx_typerep_conv";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_typerep_conv/archive/v0.14.2.tar.gz";
+        sha256 = "1g1sb3prscpa7jwnk08f50idcgyiiv0b9amkl0kymj5cghkdqw0n";
+      };
+      opamInputs = 
+      {
+        inherit (selection) typerep ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_typerep_conv/ppx_typerep_conv.v0.14.2";
+        hash = "sha256:13fsnz1ndp973s265alzn2l8r1s5bwyica864xgl247yp77f8yy2";
+      };
+    };
+    ppx_variants_conv = 
+    {
+      pname = "ppx_variants_conv";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_variants_conv/archive/v0.14.2.tar.gz";
+        sha256 = "06d63vi2ijzqa3wqnywwqywldq72karss39zi47d544y10rq4rid";
+      };
+      opamInputs = 
+      {
+        inherit (selection) variantslib ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_variants_conv/ppx_variants_conv.v0.14.2";
+        hash = "sha256:0x7xyzzdp9gpx3j32nkh8n1baw8831ppa40c5s4lb4f5gpzjg9m9";
+      };
+    };
+    ppxlib = 
+    {
+      pname = "ppxlib";
+      version = "0.24.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-ppx/ppxlib/releases/download/0.24.0/ppxlib-0.24.0.tbz";
+        sha256 = "1j4hg8gc8mkw64gvjghig1179ih90yki54hf8qxmn3yd5ry04rkp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdlib-shims sexplib0 ppx_derivers
+        ocaml-compiler-libs ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppxlib/ppxlib.0.24.0";
+        hash = "sha256:0yjsgdkfkbwyjj3yihrqnxlpagrbcr1gln7bxfmx96y3xa4fs8jv";
+      };
+    };
+    protocol_version_header = 
+    {
+      pname = "protocol_version_header";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/protocol_version_header-v0.14.0.tar.gz";
+        sha256 = "033xdykhlnpywh0bk6z5dzb5s8gf8h694pgdvnr1l50906vr7np8";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/protocol_version_header/protocol_version_header.v0.14.0";
+        hash = "sha256:1iym5ar75fsw54g94nn8qdzxabspb4xq7gzjs8nz2w15aaln89j0";
+      };
+    };
+    re = 
+    {
+      pname = "re";
+      version = "1.10.3";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/ocaml-re/releases/download/1.10.3/re-1.10.3.tbz";
+        sha256 = "1fqfg609996bgxr14yyfxhvl6hm9c1j0mm2xjdjigqrzgyb4crc4";
+      };
+      opamInputs = {
+                     inherit (selection) seq ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/re/re.1.10.3";
+        hash = "sha256:1f2xgscc07g800ia8z43i1p377dj2fjdrpzsqgzvw1dnplwnklya";
+      };
+    };
+    result = 
+    {
+      pname = "result";
+      version = "1.5";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/result/releases/download/1.5/result-1.5.tbz";
+        sha256 = "0cpfp35fdwnv3p30a06wd0py3805qxmq3jmcynjc3x2qhlimwfkw";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/result/result.1.5";
+        hash = "sha256:0ybmvlisfz5swvbcq855czz1ysv9zxmb79f1m0x8284hczmfm98f";
+      };
+    };
+    seq = 
+    {
+      pname = "seq";
+      version = "base";
+      src = null;
+      opamInputs = {
+                     inherit (selection) ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/seq/seq.base";
+        hash = "sha256:1vm8mk6zm2q3fwnkprl6jib048zr4ysldw0bl74x6wwbxj0vx6k9";
+      };
+    };
+    sexplib = 
+    {
+      pname = "sexplib";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/sexplib-v0.14.0.tar.gz";
+        sha256 = "12rlnc6fcrjfdn3gs2agi418sj54ighhs6dfll37zcv7mgywblm2";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 parsexp ocaml num dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/sexplib/sexplib.v0.14.0";
+        hash = "sha256:1nlzjkx60d4z09b15nq35ivzl6akk3svq7nl4vv5swhsmj8gvpl4";
+      };
+    };
+    sexplib0 = 
+    {
+      pname = "sexplib0";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/sexplib0-v0.14.0.tar.gz";
+        sha256 = "0adrc0r1vvvr41dcpj8jwkzh1dfgqf0mks9xlnnskqfm3a51iavg";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/sexplib0/sexplib0.v0.14.0";
+        hash = "sha256:0k9vkjbiibja48c0yayal7xwyik3h3c3v4dwd3j7jbmras63ig2c";
+      };
+    };
+    spawn = 
+    {
+      pname = "spawn";
+      version = "v0.15.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/spawn/archive/v0.15.0.tar.gz";
+        sha256 = "1isppdyahdcdv8agw1w1l3hyl6kwsbcspjw2h5rlrxn71ajv43ri";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/spawn/spawn.v0.15.0";
+        hash = "sha256:1zfg8d644i2pdq90jwblpi0y8k7xim4xb8i11czpv1qjw2p0s1y1";
+      };
+    };
+    splittable_random = 
+    {
+      pname = "splittable_random";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/splittable_random-v0.14.0.tar.gz";
+        sha256 = "185rpmdnrzs80br138pnjbx9hfp1046zvj1ap0brq1sxdwzak6lf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_sexp_message ppx_inline_test ppx_bench
+        ppx_assert ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/splittable_random/splittable_random.v0.14.0";
+        hash = "sha256:14s1ka5p5af599ira53kygzny65ls49vkxw3xk9ia5xavp7gv4bp";
+      };
+    };
+    stdio = 
+    {
+      pname = "stdio";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/stdio-v0.14.0.tar.gz";
+        sha256 = "1hj5hraprqy2i90a690l11yjszvb99j818q3d684ryx6p2lddk0l";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/stdio/stdio.v0.14.0";
+        hash = "sha256:19hlf6bgx1avq4ifwji2rj2f2j26v3nf8ywjnwh2m3dpvfqc4pvk";
+      };
+    };
+    stdlib-shims = 
+    {
+      pname = "stdlib-shims";
+      version = "0.3.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/stdlib-shims/releases/download/0.3.0/stdlib-shims-0.3.0.tbz";
+        sha256 = "0jnqsv6pqp5b5g7lcjwgd75zqqvcwcl5a32zi03zg1kvj79p5gxs";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/stdlib-shims/stdlib-shims.0.3.0";
+        hash = "sha256:19g9dnaxyh2ajz6pdczdsqzzvsmfrxwx6f613inkr31jw5hrqkiz";
+      };
+    };
+    textutils = 
+    {
+      pname = "textutils";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/textutils-v0.14.0.tar.gz";
+        sha256 = "1ss956gfk2pch3nsqis4x7z79j2d6q002bf8z8xw9z2r64wzi8hl";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel core;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/textutils/textutils.v0.14.0";
+        hash = "sha256:09ikh4xmy7ghzvz8m1p790jbhi04akarlaxqaywjl1f1qbdrhpnk";
+      };
+    };
+    time_now = 
+    {
+      pname = "time_now";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/time_now-v0.14.0.tar.gz";
+        sha256 = "0hkn2jw4dz5gflnsblskl5wp6z7zbrahwjmaxmsskfviwjg82cqh";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_optcomp ppx_base ocaml jst-config
+        jane-street-headers dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/time_now/time_now.v0.14.0";
+        hash = "sha256:1s8bqbks0cjw4x68nn5xlkykn3bcqh2rmrx6hgs53dalkiqv7ry0";
+      };
+    };
+    timezone = 
+    {
+      pname = "timezone";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/timezone-v0.14.0.tar.gz";
+        sha256 = "095xni0szjqqax2r9zh9820l72ixfga2pl0njnarp3795vkw0rdp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/timezone/timezone.v0.14.0";
+        hash = "sha256:1508a5cygb5p4n3kknx8dsrndf9x47fsq232gz4hr9pm8ipriixz";
+      };
+    };
+    topkg = 
+    {
+      pname = "topkg";
+      version = "1.0.4";
+      src = pkgs.fetchurl 
+      {
+        url = "https://erratique.ch/software/topkg/releases/topkg-1.0.4.tbz";
+        sha256 = "1kzw5cxkizcvh4rgzwgpjlj9hfxfk6yr686bxx6wrbsfs8as371k";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocamlfind ocamlbuild ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/topkg/topkg.1.0.4";
+        hash = "sha256:0gvngd4nayhhw02gcsljvmx6jkjpv9m3mqwpgimcfq04h0cf4knb";
+      };
+    };
+    typerep = 
+    {
+      pname = "typerep";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/typerep-v0.14.0.tar.gz";
+        sha256 = "0rmp5jsjg6sgn5yx0pcvch0phs7nak2fg1d48g5sjcyyyj8n1279";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/typerep/typerep.v0.14.0";
+        hash = "sha256:1hhgz8nrarcmbrnknah05wlz3yf1sq4j4mjgjajmbjnls26dkyfa";
+      };
+    };
+    uchar = 
+    {
+      pname = "uchar";
+      version = "0.0.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/uchar/releases/download/v0.0.2/uchar-0.0.2.tbz";
+        sha256 = "1w2saw7zanf9m9ffvz2lvcxvlm118pws2x1wym526xmydhqpyfa7";
+      };
+      opamInputs = {
+                     inherit (selection) ocamlbuild ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/uchar/uchar.0.0.2";
+        hash = "sha256:17sfpyj5a1z3knnjvnfa5vql6cj2x9pzgzk8w4jrvd2zii2bwpcl";
+      };
+    };
+    uutf = 
+    {
+      pname = "uutf";
+      version = "1.0.2";
+      src = pkgs.fetchurl 
+      {
+        url = "http://erratique.ch/software/uutf/releases/uutf-1.0.2.tbz";
+        sha256 = "1nx1rly3qj23jzn9yk3x6fwqimcxjd84kv5859vvhdg56psq26p6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) uchar topkg ocamlfind ocamlbuild
+        ocaml;
+        cmdliner = selection.cmdliner or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/uutf/uutf.1.0.2";
+        hash = "sha256:1j4hkk196lg1dsnf6jb1n8y3na606lkfb5vlr0gjb53qc7pdh6cy";
+      };
+    };
+    variantslib = 
+    {
+      pname = "variantslib";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/variantslib-v0.14.0.tar.gz";
+        sha256 = "11zp27gh282dx9ifbhcp6i7fkc97fvk8amaj58mf1g1hwklc0lm3";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/variantslib/variantslib.v0.14.0";
+        hash = "sha256:1g0z5w2wgsj59vrz7mdzjxdg0vxhck0q8yvzhvag77xzw85r5kjs";
+      };
+    };
+  };
+}
+
diff --git a/nix/opam-selection_4_13.nix b/nix/opam-selection_4_13.nix
new file mode 100644
index 00000000..c974185f
--- /dev/null
+++ b/nix/opam-selection_4_13.nix
@@ -0,0 +1,1822 @@
+### This file is generated by opam2nix.
+
+self:
+let
+    lib = self.lib;
+    pkgs = self.pkgs;
+    selection = self.selection;
+    repoPath = self.repoPath;
+    repos = 
+    {
+      opam-repository = 
+      rec {
+        fetch = 
+        {
+          owner = "ocaml";
+          repo = "opam-repository";
+          rev = "448eb8eb91b9e5db70daeb6fff52877ff6d72791";
+          sha256 = "1653jc4886z7spwkbfpblrjjwsfbwd0xzggrmrxfjps5a1zwi88q";
+        };
+        src = (pkgs.fetchFromGitHub) fetch;
+      };
+    };
+in
+{
+  format-version = 4;
+  inherit repos;
+  ocaml-version = "4.13.1";
+  selection = 
+  {
+    alcotest = 
+    {
+      pname = "alcotest";
+      version = "1.5.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/mirage/alcotest/releases/download/1.5.0/alcotest-js-1.5.0.tbz";
+        sha256 = "0v4ghia378g3l53r61fj98ljha0qxl82xp26y9frjy1dw03ija2l";
+      };
+      opamInputs = 
+      {
+        inherit (selection) uutf stdlib-shims re ocaml-syntax-shims ocaml fmt
+        dune cmdliner astring;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/alcotest/alcotest.1.5.0";
+        hash = "sha256:0rj1wwjawpls9y4dbq2fkw5pa2484vw5jdrw4w54ypafy8qalhk0";
+      };
+    };
+    angstrom = 
+    {
+      pname = "angstrom";
+      version = "0.15.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/angstrom/archive/0.15.0.tar.gz";
+        sha256 = "01cjjal8vjsm225v9y0q6ixam8k5f821rcr6yix6i9nzs84aq6gi";
+      };
+      opamInputs = 
+      {
+        inherit (selection) result ocaml-syntax-shims ocaml dune bigstringaf;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/angstrom/angstrom.0.15.0";
+        hash = "sha256:07ryik3g3hz79hnfdwxdh2jsw3cmbgygjs7mjdw07p927wkd83k9";
+      };
+    };
+    astring = 
+    {
+      pname = "astring";
+      version = "0.8.5";
+      src = pkgs.fetchurl 
+      {
+        url = "https://erratique.ch/software/astring/releases/astring-0.8.5.tbz";
+        sha256 = "1ykhg9gd3iy7zsgyiy2p9b1wkpqg9irw5pvcqs3sphq71iir4ml6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) topkg ocamlfind ocamlbuild ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/astring/astring.0.8.5";
+        hash = "sha256:1djnad9sq12idlakj069xvwm2nn7wqm137pqbxxai5frkgi08x74";
+      };
+    };
+    async = 
+    {
+      pname = "async";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async-v0.14.0.tar.gz";
+        sha256 = "0r6w2df5wn4xjhkhscnxrriwg19qwlxcss3srj4j5fg33jqbgwkl";
+      };
+      opamInputs = 
+      {
+        inherit (selection) textutils ppx_jane ocaml dune core_kernel core
+        async_unix async_rpc_kernel async_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async/async.v0.14.0";
+        hash = "sha256:085dsrvxlk1qmszhhi45h7z6w85fz7ik468ylx71ap3977cpayha";
+      };
+    };
+    async_kernel = 
+    {
+      pname = "async_kernel";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async_kernel-v0.14.0.tar.gz";
+        sha256 = "13k0dsbvw69jl6ckqrvigdvjffcqy778nish3370kl9lkmp0c49m";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async_kernel/async_kernel.v0.14.0";
+        hash = "sha256:185cp75vc3sgirs34xxmy5ggnvjpbj8sxxnl3p5n1v2kldf7n28j";
+      };
+    };
+    async_rpc_kernel = 
+    {
+      pname = "async_rpc_kernel";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async_rpc_kernel-v0.14.0.tar.gz";
+        sha256 = "1xrrpmhwhav3prr382q088h8sn7dax2s58hkwcv4ilcwx4zbmyk8";
+      };
+      opamInputs = 
+      {
+        inherit (selection) protocol_version_header ppx_jane ocaml dune
+        core_kernel async_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async_rpc_kernel/async_rpc_kernel.v0.14.0";
+        hash = "sha256:1l3wa564cqhjc47cwqf3a51d44cgzijmvrhjm0z0jakm6sj0rmww";
+      };
+    };
+    async_unix = 
+    {
+      pname = "async_unix";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/async_unix-v0.14.0.tar.gz";
+        sha256 = "1f9jv97xs3lgw4n7p7b95nixldh47gpbh6shcnsf0ccjxgnwx5xf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel core async_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/async_unix/async_unix.v0.14.0";
+        hash = "sha256:095m4yxgvxg2cwqa2jas6lc16w1rllzwg7v29kgbbgwlg3l91lv7";
+      };
+    };
+    base = 
+    {
+      pname = "base";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/base/archive/v0.14.2.tar.gz";
+        sha256 = "095zbz0bqrmhgw62jyhb51kqp89kph1cfcpr5ww94slr5rldpj7i";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 ocaml dune-configurator dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base/base.v0.14.2";
+        hash = "sha256:004ypm5lr9mp7glgfggi47x8h644f9z7xrx5gahsx1l82b566frv";
+      };
+    };
+    base-bytes = 
+    {
+      pname = "base-bytes";
+      version = "base";
+      src = null;
+      opamInputs = {
+                     inherit (selection) ocamlfind ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base-bytes/base-bytes.base";
+        hash = "sha256:0a68lmbf68jgm1i3b59j2sc3ha9yhv4678f9mfwwvczw88prq7l3";
+      };
+    };
+    base-threads = 
+    {
+      pname = "base-threads";
+      version = "base";
+      src = null;
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base-threads/base-threads.base";
+        hash = "sha256:1c4bpyh61ampjgk5yh3inrgcpf1z1xv0pshn54ycmpn4dyzv0p2x";
+      };
+    };
+    base-unix = 
+    {
+      pname = "base-unix";
+      version = "base";
+      src = null;
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base-unix/base-unix.base";
+        hash = "sha256:0mpsvb7684g723ylngryh15aqxg3blb7hgmq2fsqjyppr36iyzwg";
+      };
+    };
+    base_bigstring = 
+    {
+      pname = "base_bigstring";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/base_bigstring-v0.14.0.tar.gz";
+        sha256 = "1fhldk58w56ixkin763kpic512xvkkf9b4mrnjfsbm8in75kzndq";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base_bigstring/base_bigstring.v0.14.0";
+        hash = "sha256:0yn51npq4fwi9nllfhq2r3kkb17pg3igvvjgblac1g3v0nmhj6c4";
+      };
+    };
+    base_quickcheck = 
+    {
+      pname = "base_quickcheck";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/base_quickcheck/archive/v0.14.1.tar.gz";
+        sha256 = "0n5h0ysn593awvz4crkvzf5r800hd1c55bx9mm9vbqs906zii6mn";
+      };
+      opamInputs = 
+      {
+        inherit (selection) splittable_random ppxlib ppx_sexp_value
+        ppx_sexp_message ppx_let ppx_fields_conv ppx_base ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/base_quickcheck/base_quickcheck.v0.14.1";
+        hash = "sha256:0lxxagkyg1jh0x7bbps1972bid51a82m1h2x3nyz342dnsy4k6h1";
+      };
+    };
+    bigarray-compat = 
+    {
+      pname = "bigarray-compat";
+      version = "1.0.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/mirage/bigarray-compat/archive/v1.0.0.tar.gz";
+        sha256 = "1bpmmnxb1yx72aqlbdaqfl18rgz1cq9cf6cqvnfl88mz5dfr4x0d";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/bigarray-compat/bigarray-compat.1.0.0";
+        hash = "sha256:0mcg8csmd60ph17vam1s8xjsl9kp6k77i3mnkbxy0jvkn49m4a0k";
+      };
+    };
+    bigstringaf = 
+    {
+      pname = "bigstringaf";
+      version = "0.8.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/bigstringaf/archive/0.8.0.tar.gz";
+        sha256 = "06w66xnqgv8r92x50b3q6xrymry6fviyj572dw7y76cqdzfph18z";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune conf-pkg-config
+        bigarray-compat;
+        ocaml-freestanding = selection.ocaml-freestanding or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/bigstringaf/bigstringaf.0.8.0";
+        hash = "sha256:0q3v7v83pj1rf7qzqj5silkx0s8sjpkwjzkvnmnqkyp4aljqnlnb";
+      };
+    };
+    bin_prot = 
+    {
+      pname = "bin_prot";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/bin_prot-v0.14.0.tar.gz";
+        sha256 = "1f1ng6cixi3ci0nb765yfzqk9b3s752hy1i3702kh59gni1psycp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_variants_conv ppx_sexp_conv ppx_optcomp
+        ppx_fields_conv ppx_custom_printf ppx_compare ocaml dune
+        base;
+        mirage-xen-ocaml = selection.mirage-xen-ocaml or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/bin_prot/bin_prot.v0.14.0";
+        hash = "sha256:17ylwhh1kv9klavfag20n4g3175i7nmljbdj12z9yiqm4da3r4rk";
+      };
+    };
+    cmdliner = 
+    {
+      pname = "cmdliner";
+      version = "1.0.4";
+      src = pkgs.fetchurl 
+      {
+        url = "http://erratique.ch/software/cmdliner/releases/cmdliner-1.0.4.tbz";
+        sha256 = "1h04q0zkasd0mw64ggh4y58lgzkhg6yhzy60lab8k8zq9ba96ajw";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/cmdliner/cmdliner.1.0.4";
+        hash = "sha256:05qlm4yp6124w2z10dpdchldfrmgmcr6h31rnxp8qs8mk0xzx48z";
+      };
+    };
+    conf-pkg-config = 
+    {
+      pname = "conf-pkg-config";
+      version = "2";
+      src = null;
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/conf-pkg-config/conf-pkg-config.2";
+        hash = "sha256:1rli6809glz5g9xwp4wsjidc39za4n58xcpkamy6fymfnqha225n";
+      };
+      buildInputs = [ (pkgs.pkgconfig) ];
+    };
+    core = 
+    {
+      pname = "core";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/core/archive/v0.14.1.tar.gz";
+        sha256 = "1862zsk85i00vsv2chgb156b1chp8f7p508hsz6sadjx6h98q5cc";
+      };
+      opamInputs = 
+      {
+        inherit (selection) timezone spawn sexplib ppx_jane ocaml jst-config
+        dune core_kernel base-threads;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/core/core.v0.14.1";
+        hash = "sha256:13hkxn24szh9j0xl6m65k9cg8blqh44yb0nz9m5wrfbyfn8zd1hd";
+      };
+      buildInputs = [ (pkgs.linux-headers or null) ];
+    };
+    core_kernel = 
+    {
+      pname = "core_kernel";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/core_kernel/archive/v0.14.2.tar.gz";
+        sha256 = "0jyf08i9wzg3yf32f158i6n9gm751bk8zj7xqx79jnnkchwkbxb6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) variantslib typerep time_now stdio
+        splittable_random sexplib ppx_sexp_message ppx_sexp_conv ppx_optcomp
+        ppx_jane ppx_inline_test ppx_hash ppx_base ppx_assert ocaml
+        jst-config jane-street-headers fieldslib dune bin_prot
+        base_quickcheck base_bigstring base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/core_kernel/core_kernel.v0.14.2";
+        hash = "sha256:09c7k6m1vm8jhqfivn8w663v362qwjf6cb5xlzijd0sjgh1dwai5";
+      };
+    };
+    cppo = 
+    {
+      pname = "cppo";
+      version = "1.6.8";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-community/cppo/archive/v1.6.8.tar.gz";
+        sha256 = "0lxy4xkkkwgs1cj6d9lyzsqi9f6fc9r6cir5imi7yjqrpd86s1by";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune base-unix;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/cppo/cppo.1.6.8";
+        hash = "sha256:0pzd8irqkkkpfgw8nq9d21z9rj5m3qlzixyb7ybfy4b1fwh3n8bp";
+      };
+    };
+    csexp = 
+    {
+      pname = "csexp";
+      version = "1.5.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-dune/csexp/releases/download/1.5.1/csexp-1.5.1.tbz";
+        sha256 = "00mc19f89pxpmjl62862ya5kjcfrl8rjzvs00j05h2m9bw3f81fn";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/csexp/csexp.1.5.1";
+        hash = "sha256:01lc95kz13gpki4xazyh6n20kv1g9inyb5myv240wl2n9v50z8fl";
+      };
+    };
+    dune = 
+    {
+      pname = "dune";
+      version = "2.9.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/dune/releases/download/2.9.2/dune-site-2.9.2.tbz";
+        sha256 = "0ivl5r9diky8r1rfka7427kc3lh168mrz0ywdxgv8y5rgx8crrxq";
+      };
+      opamInputs = 
+      {
+        inherit (selection) base-unix
+        base-threads;
+        ocamlfind-secondary = selection.ocamlfind-secondary or null;
+        ocaml = selection.ocaml or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/dune/dune.2.9.2";
+        hash = "sha256:0qzzy2kn29ww9ryl2fvhkph9lmc112yr86xn8r8s9rbaz2zfkm6x";
+      };
+    };
+    dune-configurator = 
+    {
+      pname = "dune-configurator";
+      version = "2.9.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/dune/releases/download/2.9.1/dune-2.9.1.tbz";
+        sha256 = "09lzq04b642iy0ljp59p32lgk3q8iphjh8fkdp69q29l5frgwx5k";
+      };
+      opamInputs = 
+      {
+        inherit (selection) result ocaml dune csexp;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/dune-configurator/dune-configurator.2.9.1";
+        hash = "sha256:1aik9w82r8vbb9fsfphpb0vam68s19ggkxprnqr99ygyalp2b71j";
+      };
+    };
+    faraday = 
+    {
+      pname = "faraday";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune bigstringaf;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday/faraday.0.8.1";
+        hash = "sha256:1gk9zcifglbfnkjhndd96xf6bfp5ldmrpvvy3daidfd07l56vr96";
+      };
+    };
+    faraday-async = 
+    {
+      pname = "faraday-async";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml faraday dune core async;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday-async/faraday-async.0.8.1";
+        hash = "sha256:0vwz2qn0mmv8n4xl1jcjghnj0cfy66yq621mmhd0vgnfqyw4sysm";
+      };
+    };
+    faraday-lwt = 
+    {
+      pname = "faraday-lwt";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml lwt faraday dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday-lwt/faraday-lwt.0.8.1";
+        hash = "sha256:14nrlva43l45wp71rbyk2fb9nk43krqp292wzrlmc8ip19pc8y9p";
+      };
+    };
+    faraday-lwt-unix = 
+    {
+      pname = "faraday-lwt-unix";
+      version = "0.8.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/inhabitedtype/faraday/archive/0.8.1.tar.gz";
+        sha256 = "0yngavdplaaw5lb4ci4v4y5nvlhgan0mg1dlx1b5qdjgr83dk7cf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml lwt faraday-lwt dune base-unix;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/faraday-lwt-unix/faraday-lwt-unix.0.8.1";
+        hash = "sha256:1zfzrrbfdvw4mbmp5alkv8bmhcsfr5nillb2nj6p49fab347182m";
+      };
+    };
+    fieldslib = 
+    {
+      pname = "fieldslib";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/fieldslib-v0.14.0.tar.gz";
+        sha256 = "10n5y376fb5jgqk9h8vq158rm1b36h9lzh6p11q33h6xgvb1v6n3";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/fieldslib/fieldslib.v0.14.0";
+        hash = "sha256:1gsrbs4x45k4bp1zih9c6db3axhaiy91knac6bk6hpgv9sjalicm";
+      };
+    };
+    fmt = 
+    {
+      pname = "fmt";
+      version = "0.9.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://erratique.ch/software/fmt/releases/fmt-0.9.0.tbz";
+        sha256 = "0q8j2in2473xh7k4hfgnppv9qy77f2ih89yp6yhpbp92ba021yzi";
+      };
+      opamInputs = 
+      {
+        inherit (selection) topkg ocamlfind ocamlbuild
+        ocaml;
+        cmdliner = selection.cmdliner or null;
+        base-unix = selection.base-unix or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/fmt/fmt.0.9.0";
+        hash = "sha256:1czh5i3i4mkf9xfasji3v7n821qmnnandlklh67ali0x87brldny";
+      };
+    };
+    httpaf = 
+    {
+      pname = "httpaf";
+      version = "development";
+      src = self.directSrc "httpaf";
+      opamInputs = 
+      {
+        inherit (selection) result ocaml faraday dune bigstringaf angstrom;
+      };
+      opamSrc = "httpaf.opam";
+    };
+    httpaf-async = 
+    {
+      pname = "httpaf-async";
+      version = "development";
+      src = self.directSrc "httpaf-async";
+      opamInputs = 
+      {
+        inherit (selection) ocaml httpaf faraday-async dune async;
+      };
+      opamSrc = "httpaf-async.opam";
+    };
+    httpaf-lwt-unix = 
+    {
+      pname = "httpaf-lwt-unix";
+      version = "development";
+      src = self.directSrc "httpaf-lwt-unix";
+      opamInputs = 
+      {
+        inherit (selection) ocaml lwt httpaf faraday-lwt-unix dune;
+      };
+      opamSrc = "httpaf-lwt-unix.opam";
+    };
+    jane-street-headers = 
+    {
+      pname = "jane-street-headers";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/jane-street-headers-v0.14.0.tar.gz";
+        sha256 = "028yxb4h3iy025iy89v8653m5brh7flrjshghs4x99pd690pmfs7";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/jane-street-headers/jane-street-headers.v0.14.0";
+        hash = "sha256:1w6zjjmyszk9pax139rkxb3vx0w23w0pfd46bddfyfkxq2rbwsvf";
+      };
+    };
+    jst-config = 
+    {
+      pname = "jst-config";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/jst-config/archive/refs/tags/v0.14.1.tar.gz";
+        sha256 = "0wdjs0lvc5wbggh27cf490jarfibrrb5xxsrigg41m32kjkbijm4";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio ppx_assert ocaml dune-configurator dune
+        base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/jst-config/jst-config.v0.14.1";
+        hash = "sha256:0myym84b9yx4vqa0ml0zf3cx6rms3g5dv704vhf5bpr7jnqz0qcb";
+      };
+    };
+    lwt = 
+    {
+      pname = "lwt";
+      version = "5.5.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocsigen/lwt/archive/refs/tags/5.5.0.tar.gz";
+        sha256 = "15gr6nhhfjyh91v9chvm6j7vnp1hhc60y3plgvcgl5yl5k7xbbj9";
+      };
+      opamInputs = 
+      {
+        inherit (selection) seq result ocplib-endian ocaml mmap
+        dune-configurator dune
+        cppo;
+        ocaml-syntax-shims = selection.ocaml-syntax-shims or null;
+        conf-libev = selection.conf-libev or null;
+        base-unix = selection.base-unix or null;
+        base-threads = selection.base-threads or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/lwt/lwt.5.5.0";
+        hash = "sha256:0iadlycd4q93lsk07k9zaimlysgd38sj6v50dc3cb491vl0icipz";
+      };
+    };
+    mmap = 
+    {
+      pname = "mmap";
+      version = "1.1.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/mirage/mmap/releases/download/v1.1.0/mmap-v1.1.0.tbz";
+        sha256 = "0l6waidal2n8mkdn74avbslvc10sf49f5d889n838z03pra5chsc";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/mmap/mmap.1.1.0";
+        hash = "sha256:1snhaf6mixmmb49gcin5wmbz4bfjz406mip4556lids8ajm22ibh";
+      };
+    };
+    num = 
+    {
+      pname = "num";
+      version = "1.4";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/num/archive/v1.4.tar.gz";
+        sha256 = "090gl27g84r3s2b12vgkz8fp269jqlrhx4lpg7008yviisv8hl01";
+      };
+      opamInputs = {
+                     inherit (selection) ocamlfind ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/num/num.1.4";
+        hash = "sha256:04wb8ww165lsifn36jcrxw5zs87id5kib6rilq6zh6qhzvij88pf";
+      };
+    };
+    ocaml = 
+    {
+      pname = "ocaml";
+      version = "4.13.1";
+      src = null;
+      opamInputs = 
+      {
+        inherit (selection)
+        ocaml-config;
+        ocaml-variants = selection.ocaml-variants or null;
+        ocaml-system = selection.ocaml-system or null;
+        ocaml-base-compiler = selection.ocaml-base-compiler or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml/ocaml.4.13.1";
+        hash = "sha256:12aajj2hc636jr6wbv4vba8pmjdndbcvnw7q35gj4agxmrjspziw";
+      };
+    };
+    ocaml-base-compiler = 
+    {
+      pname = "ocaml-base-compiler";
+      version = "4.13.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/ocaml/archive/4.13.1.tar.gz";
+        sha256 = "1i7ad8lh5l74wb3yzmhlv529wc75a5sjybzkad7wdl8zrj47jk0r";
+      };
+      opamInputs = {
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-base-compiler/ocaml-base-compiler.4.13.1";
+        hash = "sha256:069i5vsndd9lsvdm5wk898nfnc85ww7459nibjg6881ww43w8ck1";
+      };
+    };
+    ocaml-compiler-libs = 
+    {
+      pname = "ocaml-compiler-libs";
+      version = "v0.12.4";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ocaml-compiler-libs/releases/download/v0.12.4/ocaml-compiler-libs-v0.12.4.tbz";
+        sha256 = "0q3pl20pkx410gw9g4m26qq6dmzi9qan2dqlga6c2ifc6pnckjaf";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-compiler-libs/ocaml-compiler-libs.v0.12.4";
+        hash = "sha256:1blynia10j8vyj559kcvc7ic69zq6qjjn092fcsjzfw6czd8ya2c";
+      };
+    };
+    ocaml-config = 
+    {
+      pname = "ocaml-config";
+      version = "2";
+      src = null;
+      opamInputs = 
+      {
+        ocaml-variants = selection.ocaml-variants or null;
+        ocaml-system = selection.ocaml-system or null;
+        ocaml-base-compiler = selection.ocaml-base-compiler or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-config/ocaml-config.2";
+        hash = "sha256:0h0hgqq9mbywvqygppfdc50gf9ss8a97l4dgsv3hszmzh6gglgrg";
+      };
+    };
+    ocaml-syntax-shims = 
+    {
+      pname = "ocaml-syntax-shims";
+      version = "1.0.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-ppx/ocaml-syntax-shims/releases/download/1.0.0/ocaml-syntax-shims-1.0.0.tbz";
+        sha256 = "1j7848khli4p7j8i2kmnvhdnhcwhy3zgdpf5ds5ic30ax69y3cl9";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocaml-syntax-shims/ocaml-syntax-shims.1.0.0";
+        hash = "sha256:0qnm1db0298yqcn6j9fmb0l4gr5nhcar8plskj39917invyamgd2";
+      };
+    };
+    ocamlbuild = 
+    {
+      pname = "ocamlbuild";
+      version = "0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/ocamlbuild/archive/0.14.0.tar.gz";
+        sha256 = "0y1fskw9rg2y1zgb7whv3v8v4xw04svgxslf3856q2aqd7lrrcl7";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocamlbuild/ocamlbuild.0.14.0";
+        hash = "sha256:1r5qnrcxfypzyvjvb3zd9f66kr5ldxdl3g9rsi3pb6040krqb5w7";
+      };
+    };
+    ocamlfind = 
+    {
+      pname = "ocamlfind";
+      version = "1.9.3";
+      src = pkgs.fetchurl 
+      {
+        url = "http://download.camlcity.org/download/findlib-1.9.3.tar.gz";
+        sha256 = "0hfcwamcvinmww59b5i4yxbf0kxyzkp5qv3d1c7ybn9q52vgq463";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml;
+        graphics = selection.graphics or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocamlfind/ocamlfind.1.9.3";
+        hash = "sha256:1wq1lkw3rpgilprlakznsxxf60mcidn3fzi3vjrgjdrnnp9hvh19";
+      };
+    };
+    ocplib-endian = 
+    {
+      pname = "ocplib-endian";
+      version = "1.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/OCamlPro/ocplib-endian/archive/refs/tags/1.2.tar.gz";
+        sha256 = "085kskr0cxcnv2d62n3jq1r273p7giisy56zfl26mm7amvl79blp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocaml dune cppo base-bytes;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ocplib-endian/ocplib-endian.1.2";
+        hash = "sha256:1jldvb471gyhkrzwfvqg722l3a8dc37hhhyas66skjzfmqyi2pnh";
+      };
+    };
+    octavius = 
+    {
+      pname = "octavius";
+      version = "1.2.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-doc/octavius/archive/v1.2.2.tar.gz";
+        sha256 = "1bg0fcm7haqxvx5wx2cci0mbbq0gf1vw9fa4kkd6jsriw1611jga";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/octavius/octavius.1.2.2";
+        hash = "sha256:0bagilkanfjyi56hrk9dw43xs6zry9p8n3l55r3d58v5hz2xsbwl";
+      };
+    };
+    parsexp = 
+    {
+      pname = "parsexp";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/parsexp/archive/refs/tags/v0.14.2.tar.gz";
+        sha256 = "0c7jl6sqfawqpvbhci8vyyhgvcyd3lw5lj3jcf5f1p6w1177xqgn";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/parsexp/parsexp.v0.14.2";
+        hash = "sha256:1fqnxdr1pgxmada77hkhyyr7yybpv2f810shnhvhkpw15h58azx1";
+      };
+    };
+    ppx_assert = 
+    {
+      pname = "ppx_assert";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_assert-v0.14.0.tar.gz";
+        sha256 = "1l2rr4jz2q5b35ryn2z146z7m9v6k8krp5gpn8ilib66mnz5zx15";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_here ppx_compare
+        ppx_cold ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_assert/ppx_assert.v0.14.0";
+        hash = "sha256:1ry1bqssjw5lc7h0x2cc7f8rmz807j5l7029lxd4i12vgq91x5km";
+      };
+    };
+    ppx_base = 
+    {
+      pname = "ppx_base";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_base-v0.14.0.tar.gz";
+        sha256 = "0b7a3fmi90jk8paz0g36yzaq670fbnrbi1j8r5ibh9wbcfli7ji6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_js_style ppx_hash
+        ppx_enumerate ppx_compare ppx_cold ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_base/ppx_base.v0.14.0";
+        hash = "sha256:1n66x8xl2n0qbq1g0b1l3nsdqlb3czj5w509riwqdgz11fyrzi25";
+      };
+    };
+    ppx_bench = 
+    {
+      pname = "ppx_bench";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_bench/archive/v0.14.1.tar.gz";
+        sha256 = "1jr3cf4zsk894x64c8ir9ap9l412q35b2605pr7flrlxbm4vkf3f";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_inline_test ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_bench/ppx_bench.v0.14.1";
+        hash = "sha256:0r17lcfhxd14ihbbhqjqjmx26ig4xf62dmc2pblg7flzcf4k64dp";
+      };
+    };
+    ppx_bin_prot = 
+    {
+      pname = "ppx_bin_prot";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_bin_prot-v0.14.0.tar.gz";
+        sha256 = "0wa2jmvm2k88b37pbcafy1mdf5iaip0yxg5dw774sbh28nm08m2s";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_here ocaml dune bin_prot base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_bin_prot/ppx_bin_prot.v0.14.0";
+        hash = "sha256:0rsbhajm4927f1798baalwf3f7f5vs8jy27bxd6rhhybnvqjxyj9";
+      };
+    };
+    ppx_cold = 
+    {
+      pname = "ppx_cold";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_cold-v0.14.0.tar.gz";
+        sha256 = "1madfzhpir9amnxmg530n70vll0jrl59vyp71miji73i6b9sy6n2";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_cold/ppx_cold.v0.14.0";
+        hash = "sha256:0g566vskiblrxr246c3s26rlzxciln518fr4f6d8lid63qgrgnfm";
+      };
+    };
+    ppx_compare = 
+    {
+      pname = "ppx_compare";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_compare-v0.14.0.tar.gz";
+        sha256 = "0mqxa2s194nif7x4fjn1p5gd9i3bakr8nv27gf8x1g5nmi8q9pmp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_compare/ppx_compare.v0.14.0";
+        hash = "sha256:1ndfsgazb7yg5q3aqzcrnr914sf615bsh4z4q202bdvpf0fqj31k";
+      };
+    };
+    ppx_custom_printf = 
+    {
+      pname = "ppx_custom_printf";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_custom_printf/archive/v0.14.1.tar.gz";
+        sha256 = "0kzbckbvhfn3s9an1hq01qd5iac7wgirw182ablpqxc6r3dmijrl";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_custom_printf/ppx_custom_printf.v0.14.1";
+        hash = "sha256:1karjqaa17ai6v4y7wb2zwfpscyirmb4ixdr3lw6i83icklsgmdw";
+      };
+    };
+    ppx_derivers = 
+    {
+      pname = "ppx_derivers";
+      version = "1.2.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-ppx/ppx_derivers/archive/1.2.1.tar.gz";
+        sha256 = "159vqy616ni18mn0dlv8c2y4h7mb4hahwjn53yrr59yyhzhmwndn";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_derivers/ppx_derivers.1.2.1";
+        hash = "sha256:1hj1ina0n7pgz16mrvijczapw75pd0hif0i18dpw7d1fyg2qr8py";
+      };
+    };
+    ppx_enumerate = 
+    {
+      pname = "ppx_enumerate";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_enumerate-v0.14.0.tar.gz";
+        sha256 = "1ij6sffgqhnjwnj9brhrrw1c6xgxlh0s6r17x1qkgnyrc73gfsz8";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_enumerate/ppx_enumerate.v0.14.0";
+        hash = "sha256:0lgnrpq1vmb44367y7mdr7jw1yqmy08fi6phgq8pch3a47fdk2rm";
+      };
+    };
+    ppx_expect = 
+    {
+      pname = "ppx_expect";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_expect/archive/v0.14.2.tar.gz";
+        sha256 = "1gcjlya6knnsrl60sd3vlgp7arj39xm5fjjfk5sick4z66agm2n5";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio re ppxlib ppx_inline_test ppx_here ocaml
+        dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_expect/ppx_expect.v0.14.2";
+        hash = "sha256:14hnawvs9fc87kghg00zj0p1p21f22gdy1767l2nwb4ihl3h133b";
+      };
+    };
+    ppx_fields_conv = 
+    {
+      pname = "ppx_fields_conv";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_fields_conv/archive/v0.14.2.tar.gz";
+        sha256 = "0r7d51j54r1za6bwqsmhmhhfab8n10zyk5zznhkm91f20dx9ddip";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml fieldslib dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_fields_conv/ppx_fields_conv.v0.14.2";
+        hash = "sha256:0332mrn1xk3423rm4hk5lif9igrj3339xyfd6464wcbkpakivfba";
+      };
+    };
+    ppx_fixed_literal = 
+    {
+      pname = "ppx_fixed_literal";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_fixed_literal-v0.14.0.tar.gz";
+        sha256 = "0w0a06143mhmczbpr0lfb66r6im7075gck4p0idbcari63sximqj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_fixed_literal/ppx_fixed_literal.v0.14.0";
+        hash = "sha256:13wng3z0x3fx6l4vym8rddc0yniplim94gn5x8bcfkjd2yhxd88s";
+      };
+    };
+    ppx_hash = 
+    {
+      pname = "ppx_hash";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_hash-v0.14.0.tar.gz";
+        sha256 = "0x4wgdvhgd8a49bzari52jpkykxpv6ncgp5ncda3xgg0a9r49s8n";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_compare ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_hash/ppx_hash.v0.14.0";
+        hash = "sha256:0zcnsd0724w6kpx4w1i3nbfrvffhnqjn3rinddgqjndx5pvghrlc";
+      };
+    };
+    ppx_here = 
+    {
+      pname = "ppx_here";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_here-v0.14.0.tar.gz";
+        sha256 = "0b444djy68v6ji0ypwv5l02pkl151qzrgg96lyhl8dxfrzvj1zkj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_here/ppx_here.v0.14.0";
+        hash = "sha256:0f7p619ymqm27iclcx3cbyyn1k0mccw9vsa0l88m1jk3kjgjbmzz";
+      };
+    };
+    ppx_inline_test = 
+    {
+      pname = "ppx_inline_test";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_inline_test/archive/v0.14.1.tar.gz";
+        sha256 = "0qzvm8rg07annl8zpqlhzx1z8ahrrf02r1brd43ykqas5sww3rfp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) time_now ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_inline_test/ppx_inline_test.v0.14.1";
+        hash = "sha256:1vwg8bgw093ia075n7vh0kl82sjd5r9yk27s45ljzz9cmfqrr4sa";
+      };
+    };
+    ppx_jane = 
+    {
+      pname = "ppx_jane";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_jane-v0.14.0.tar.gz";
+        sha256 = "18js98xdqf8d54sjn1gccjkwbv2p56qy7bhvjgk94pr3fipfz0v7";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_variants_conv ppx_typerep_conv
+        ppx_string ppx_stable ppx_sexp_value ppx_sexp_message ppx_pipebang
+        ppx_optional ppx_optcomp ppx_module_timer ppx_let ppx_inline_test
+        ppx_here ppx_fixed_literal ppx_fields_conv ppx_expect
+        ppx_custom_printf ppx_bin_prot ppx_bench ppx_base ppx_assert ocaml
+        dune base_quickcheck;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_jane/ppx_jane.v0.14.0";
+        hash = "sha256:1jqzfdg3rbb96mgw0cpbsmr1y06whhqys6a4rkfdih6z4n5cm4ns";
+      };
+    };
+    ppx_js_style = 
+    {
+      pname = "ppx_js_style";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_js_style/archive/refs/tags/v0.14.1.tar.gz";
+        sha256 = "1nq4rj659f34dc28pj7ir2szqbpky4nzs9qfw0am6sf36jwispiw";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib octavius ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_js_style/ppx_js_style.v0.14.1";
+        hash = "sha256:05bc07ghvfd4d85inf1qvpqxphvcg7mgf8fn9ycib6fdmxdkkamq";
+      };
+    };
+    ppx_let = 
+    {
+      pname = "ppx_let";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_let-v0.14.0.tar.gz";
+        sha256 = "1qcrnd86pbr1di5m6z4ps4p15qawwa02jxwz3xfd82hdbjmdwf1s";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_let/ppx_let.v0.14.0";
+        hash = "sha256:1n3ayvvmiwmv5jnyjl8nr510dblijwx9g2r39hl5xxgr57d4c7f7";
+      };
+    };
+    ppx_module_timer = 
+    {
+      pname = "ppx_module_timer";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_module_timer-v0.14.0.tar.gz";
+        sha256 = "04a7vzk4s3jn6wj94q0hn8kd9vxlzkpcq5ifpvz3bdfgmypjks5z";
+      };
+      opamInputs = 
+      {
+        inherit (selection) time_now stdio ppxlib ppx_base ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_module_timer/ppx_module_timer.v0.14.0";
+        hash = "sha256:18q8zyppvl9wskx5flhcfmkznzihfs3kk3c38n0kdh1ngg6c1prr";
+      };
+    };
+    ppx_optcomp = 
+    {
+      pname = "ppx_optcomp";
+      version = "v0.14.3";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_optcomp/archive/v0.14.3.tar.gz";
+        sha256 = "0bxzh0pm3zdiadrd37jjzp7zm2qn28mx25ahk0shgfb73vya809n";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_optcomp/ppx_optcomp.v0.14.3";
+        hash = "sha256:0xh7m3hsm7vrhzmd86n3irhydp9lyr23ax9mg1khq2jhcbyqqvy0";
+      };
+    };
+    ppx_optional = 
+    {
+      pname = "ppx_optional";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_optional-v0.14.0.tar.gz";
+        sha256 = "1hh6ivlp1qpvyn8l0vhrahkkcp3scf7km254sgplprmk10wnyidz";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_optional/ppx_optional.v0.14.0";
+        hash = "sha256:0jg35ql4vwzh27hv2vn52hilfb2cpdl91wiaj0r6nh9s6iwy8dzf";
+      };
+    };
+    ppx_pipebang = 
+    {
+      pname = "ppx_pipebang";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_pipebang-v0.14.0.tar.gz";
+        sha256 = "19afbbvy72i1347prvkpy3ms75xnk7kl2hn83h40p6yh27100hky";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_pipebang/ppx_pipebang.v0.14.0";
+        hash = "sha256:1rklw915zv3apij5icp19337aza8di19sp86qp0w6lwimmdvx7dn";
+      };
+    };
+    ppx_sexp_conv = 
+    {
+      pname = "ppx_sexp_conv";
+      version = "v0.14.3";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_sexp_conv/archive/v0.14.3.tar.gz";
+        sha256 = "0fbnkhsd6yphc49pa21nlmbik99n7qkaz8l9paq96v012ipg9h9g";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_sexp_conv/ppx_sexp_conv.v0.14.3";
+        hash = "sha256:03c4ar76g1sz2y35a9jbffw957i17ixwd7ky8cg5ss7m7jl7x1fs";
+      };
+    };
+    ppx_sexp_message = 
+    {
+      pname = "ppx_sexp_message";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_sexp_message/archive/v0.14.1.tar.gz";
+        sha256 = "06d1cx8nh6chgx09lqjgsagc02lfsvv18fydrviqjvydx52m2qjf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_here ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_sexp_message/ppx_sexp_message.v0.14.1";
+        hash = "sha256:0djv8npvc7lx1d20f3ln3s3hffh729fpyyj156fpylkqnr9lcfv7";
+      };
+    };
+    ppx_sexp_value = 
+    {
+      pname = "ppx_sexp_value";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/ppx_sexp_value-v0.14.0.tar.gz";
+        sha256 = "0yc6i1yx9mb8pwjkswy09aqg5kz1hgrpjyniq2v6whfjvxl1qrkj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ppx_sexp_conv ppx_here ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_sexp_value/ppx_sexp_value.v0.14.0";
+        hash = "sha256:0wqj7nr9nvyss3qjf5jcbijjqkrah2ib8ypfp4hxw00vmyfvyrps";
+      };
+    };
+    ppx_stable = 
+    {
+      pname = "ppx_stable";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_stable/archive/v0.14.1.tar.gz";
+        sha256 = "1dw8ilrvi5lssxnbflnzskmyi3k93ij2kbyz49y93agv0b8dsq01";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_stable/ppx_stable.v0.14.1";
+        hash = "sha256:1b2kvif9jc2wj99ciaz6876myn05qbk3a7gn40msnpmd9prgg1lc";
+      };
+    };
+    ppx_string = 
+    {
+      pname = "ppx_string";
+      version = "v0.14.1";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_string/archive/v0.14.1.tar.gz";
+        sha256 = "1a8f7bplbxvwm4lh0m57j89jkwkxfm9r5ndcvvlj5v6py8pv69wj";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdio ppxlib ppx_base ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_string/ppx_string.v0.14.1";
+        hash = "sha256:0adczy40rfpif3jwz2vrhf8kphzilvgffws2si9ypzs264ipjvg8";
+      };
+    };
+    ppx_typerep_conv = 
+    {
+      pname = "ppx_typerep_conv";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_typerep_conv/archive/v0.14.2.tar.gz";
+        sha256 = "1g1sb3prscpa7jwnk08f50idcgyiiv0b9amkl0kymj5cghkdqw0n";
+      };
+      opamInputs = 
+      {
+        inherit (selection) typerep ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_typerep_conv/ppx_typerep_conv.v0.14.2";
+        hash = "sha256:13fsnz1ndp973s265alzn2l8r1s5bwyica864xgl247yp77f8yy2";
+      };
+    };
+    ppx_variants_conv = 
+    {
+      pname = "ppx_variants_conv";
+      version = "v0.14.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/ppx_variants_conv/archive/v0.14.2.tar.gz";
+        sha256 = "06d63vi2ijzqa3wqnywwqywldq72karss39zi47d544y10rq4rid";
+      };
+      opamInputs = 
+      {
+        inherit (selection) variantslib ppxlib ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppx_variants_conv/ppx_variants_conv.v0.14.2";
+        hash = "sha256:0x7xyzzdp9gpx3j32nkh8n1baw8831ppa40c5s4lb4f5gpzjg9m9";
+      };
+    };
+    ppxlib = 
+    {
+      pname = "ppxlib";
+      version = "0.24.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml-ppx/ppxlib/releases/download/0.24.0/ppxlib-0.24.0.tbz";
+        sha256 = "1j4hg8gc8mkw64gvjghig1179ih90yki54hf8qxmn3yd5ry04rkp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) stdlib-shims sexplib0 ppx_derivers
+        ocaml-compiler-libs ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/ppxlib/ppxlib.0.24.0";
+        hash = "sha256:0yjsgdkfkbwyjj3yihrqnxlpagrbcr1gln7bxfmx96y3xa4fs8jv";
+      };
+    };
+    protocol_version_header = 
+    {
+      pname = "protocol_version_header";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/protocol_version_header-v0.14.0.tar.gz";
+        sha256 = "033xdykhlnpywh0bk6z5dzb5s8gf8h694pgdvnr1l50906vr7np8";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/protocol_version_header/protocol_version_header.v0.14.0";
+        hash = "sha256:1iym5ar75fsw54g94nn8qdzxabspb4xq7gzjs8nz2w15aaln89j0";
+      };
+    };
+    re = 
+    {
+      pname = "re";
+      version = "1.10.3";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/ocaml-re/releases/download/1.10.3/re-1.10.3.tbz";
+        sha256 = "1fqfg609996bgxr14yyfxhvl6hm9c1j0mm2xjdjigqrzgyb4crc4";
+      };
+      opamInputs = {
+                     inherit (selection) seq ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/re/re.1.10.3";
+        hash = "sha256:1f2xgscc07g800ia8z43i1p377dj2fjdrpzsqgzvw1dnplwnklya";
+      };
+    };
+    result = 
+    {
+      pname = "result";
+      version = "1.5";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/result/releases/download/1.5/result-1.5.tbz";
+        sha256 = "0cpfp35fdwnv3p30a06wd0py3805qxmq3jmcynjc3x2qhlimwfkw";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/result/result.1.5";
+        hash = "sha256:0ybmvlisfz5swvbcq855czz1ysv9zxmb79f1m0x8284hczmfm98f";
+      };
+    };
+    seq = 
+    {
+      pname = "seq";
+      version = "base";
+      src = null;
+      opamInputs = {
+                     inherit (selection) ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/seq/seq.base";
+        hash = "sha256:1vm8mk6zm2q3fwnkprl6jib048zr4ysldw0bl74x6wwbxj0vx6k9";
+      };
+    };
+    sexplib = 
+    {
+      pname = "sexplib";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/sexplib-v0.14.0.tar.gz";
+        sha256 = "12rlnc6fcrjfdn3gs2agi418sj54ighhs6dfll37zcv7mgywblm2";
+      };
+      opamInputs = 
+      {
+        inherit (selection) sexplib0 parsexp ocaml num dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/sexplib/sexplib.v0.14.0";
+        hash = "sha256:1nlzjkx60d4z09b15nq35ivzl6akk3svq7nl4vv5swhsmj8gvpl4";
+      };
+    };
+    sexplib0 = 
+    {
+      pname = "sexplib0";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/sexplib0-v0.14.0.tar.gz";
+        sha256 = "0adrc0r1vvvr41dcpj8jwkzh1dfgqf0mks9xlnnskqfm3a51iavg";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/sexplib0/sexplib0.v0.14.0";
+        hash = "sha256:0k9vkjbiibja48c0yayal7xwyik3h3c3v4dwd3j7jbmras63ig2c";
+      };
+    };
+    spawn = 
+    {
+      pname = "spawn";
+      version = "v0.15.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/janestreet/spawn/archive/v0.15.0.tar.gz";
+        sha256 = "1isppdyahdcdv8agw1w1l3hyl6kwsbcspjw2h5rlrxn71ajv43ri";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/spawn/spawn.v0.15.0";
+        hash = "sha256:1zfg8d644i2pdq90jwblpi0y8k7xim4xb8i11czpv1qjw2p0s1y1";
+      };
+    };
+    splittable_random = 
+    {
+      pname = "splittable_random";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/splittable_random-v0.14.0.tar.gz";
+        sha256 = "185rpmdnrzs80br138pnjbx9hfp1046zvj1ap0brq1sxdwzak6lf";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_sexp_message ppx_inline_test ppx_bench
+        ppx_assert ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/splittable_random/splittable_random.v0.14.0";
+        hash = "sha256:14s1ka5p5af599ira53kygzny65ls49vkxw3xk9ia5xavp7gv4bp";
+      };
+    };
+    stdio = 
+    {
+      pname = "stdio";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/stdio-v0.14.0.tar.gz";
+        sha256 = "1hj5hraprqy2i90a690l11yjszvb99j818q3d684ryx6p2lddk0l";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/stdio/stdio.v0.14.0";
+        hash = "sha256:19hlf6bgx1avq4ifwji2rj2f2j26v3nf8ywjnwh2m3dpvfqc4pvk";
+      };
+    };
+    stdlib-shims = 
+    {
+      pname = "stdlib-shims";
+      version = "0.3.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/stdlib-shims/releases/download/0.3.0/stdlib-shims-0.3.0.tbz";
+        sha256 = "0jnqsv6pqp5b5g7lcjwgd75zqqvcwcl5a32zi03zg1kvj79p5gxs";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/stdlib-shims/stdlib-shims.0.3.0";
+        hash = "sha256:19g9dnaxyh2ajz6pdczdsqzzvsmfrxwx6f613inkr31jw5hrqkiz";
+      };
+    };
+    textutils = 
+    {
+      pname = "textutils";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/textutils-v0.14.0.tar.gz";
+        sha256 = "1ss956gfk2pch3nsqis4x7z79j2d6q002bf8z8xw9z2r64wzi8hl";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel core;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/textutils/textutils.v0.14.0";
+        hash = "sha256:09ikh4xmy7ghzvz8m1p790jbhi04akarlaxqaywjl1f1qbdrhpnk";
+      };
+    };
+    time_now = 
+    {
+      pname = "time_now";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/time_now-v0.14.0.tar.gz";
+        sha256 = "0hkn2jw4dz5gflnsblskl5wp6z7zbrahwjmaxmsskfviwjg82cqh";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_optcomp ppx_base ocaml jst-config
+        jane-street-headers dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/time_now/time_now.v0.14.0";
+        hash = "sha256:1s8bqbks0cjw4x68nn5xlkykn3bcqh2rmrx6hgs53dalkiqv7ry0";
+      };
+    };
+    timezone = 
+    {
+      pname = "timezone";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/timezone-v0.14.0.tar.gz";
+        sha256 = "095xni0szjqqax2r9zh9820l72ixfga2pl0njnarp3795vkw0rdp";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ppx_jane ocaml dune core_kernel;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/timezone/timezone.v0.14.0";
+        hash = "sha256:1508a5cygb5p4n3kknx8dsrndf9x47fsq232gz4hr9pm8ipriixz";
+      };
+    };
+    topkg = 
+    {
+      pname = "topkg";
+      version = "1.0.4";
+      src = pkgs.fetchurl 
+      {
+        url = "https://erratique.ch/software/topkg/releases/topkg-1.0.4.tbz";
+        sha256 = "1kzw5cxkizcvh4rgzwgpjlj9hfxfk6yr686bxx6wrbsfs8as371k";
+      };
+      opamInputs = 
+      {
+        inherit (selection) ocamlfind ocamlbuild ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/topkg/topkg.1.0.4";
+        hash = "sha256:0gvngd4nayhhw02gcsljvmx6jkjpv9m3mqwpgimcfq04h0cf4knb";
+      };
+    };
+    typerep = 
+    {
+      pname = "typerep";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/typerep-v0.14.0.tar.gz";
+        sha256 = "0rmp5jsjg6sgn5yx0pcvch0phs7nak2fg1d48g5sjcyyyj8n1279";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/typerep/typerep.v0.14.0";
+        hash = "sha256:1hhgz8nrarcmbrnknah05wlz3yf1sq4j4mjgjajmbjnls26dkyfa";
+      };
+    };
+    uchar = 
+    {
+      pname = "uchar";
+      version = "0.0.2";
+      src = pkgs.fetchurl 
+      {
+        url = "https://github.com/ocaml/uchar/releases/download/v0.0.2/uchar-0.0.2.tbz";
+        sha256 = "1w2saw7zanf9m9ffvz2lvcxvlm118pws2x1wym526xmydhqpyfa7";
+      };
+      opamInputs = {
+                     inherit (selection) ocamlbuild ocaml;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/uchar/uchar.0.0.2";
+        hash = "sha256:17sfpyj5a1z3knnjvnfa5vql6cj2x9pzgzk8w4jrvd2zii2bwpcl";
+      };
+    };
+    uutf = 
+    {
+      pname = "uutf";
+      version = "1.0.2";
+      src = pkgs.fetchurl 
+      {
+        url = "http://erratique.ch/software/uutf/releases/uutf-1.0.2.tbz";
+        sha256 = "1nx1rly3qj23jzn9yk3x6fwqimcxjd84kv5859vvhdg56psq26p6";
+      };
+      opamInputs = 
+      {
+        inherit (selection) uchar topkg ocamlfind ocamlbuild
+        ocaml;
+        cmdliner = selection.cmdliner or null;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/uutf/uutf.1.0.2";
+        hash = "sha256:1j4hkk196lg1dsnf6jb1n8y3na606lkfb5vlr0gjb53qc7pdh6cy";
+      };
+    };
+    variantslib = 
+    {
+      pname = "variantslib";
+      version = "v0.14.0";
+      src = pkgs.fetchurl 
+      {
+        url = "https://ocaml.janestreet.com/ocaml-core/v0.14/files/variantslib-v0.14.0.tar.gz";
+        sha256 = "11zp27gh282dx9ifbhcp6i7fkc97fvk8amaj58mf1g1hwklc0lm3";
+      };
+      opamInputs = {
+                     inherit (selection) ocaml dune base;
+      };
+      opamSrc = repoPath (repos.opam-repository.src) 
+      {
+        package = "packages/variantslib/variantslib.v0.14.0";
+        hash = "sha256:1g0z5w2wgsj59vrz7mdzjxdg0vxhck0q8yvzhvag77xzw85r5kjs";
+      };
+    };
+  };
+}
+
diff --git a/nix/opam2nix.nix b/nix/opam2nix.nix
new file mode 100644
index 00000000..da196583
--- /dev/null
+++ b/nix/opam2nix.nix
@@ -0,0 +1,4 @@
+{ source ? builtins.fetchTarball "https://github.com/timbertson/opam2nix/archive/v1.tar.gz"
+, pkgs
+, ocamlPackagesOverride }:
+import source { inherit pkgs ocamlPackagesOverride; }
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 00000000..b01b43a6
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,10 @@
+{ pkgs ? import <nixpkgs> {}
+, ocamlVersion ? import ./nix/ocamlDefaultVersion.nix }:
+let
+  ocamlPackages = pkgs.ocaml-ng."ocamlPackages_${ocamlVersion}";
+  local = pkgs.callPackage ./. { inherit ocamlVersion; };
+in
+pkgs.mkShell {
+  inputsFrom = with local; [ httpaf httpaf-lwt-unix httpaf-async ];
+  buildInputs = [ ocamlPackages.ocaml-lsp ] ++ local.testPackages;
+}