nix2js

This is an experiment to try to transpile nix expressions to JavaScript and execute them via NodeJS.

This currently evaluates everything strictly, but encapsulates it using promises, which gives a kind of non-strict eval with regards to assertions and other exceptions.

The (target/release)nix2js executable can be built using:

cargo build --release

WASM

The wasm version of nix2js can be built (requires wasm-pack, and it's dependencies) using:

(cd wasm && wasm-pack build --target node)

The resulting code is then (if successful) present in wasm/pkg.

REPL

npm i
# this calls tsc and wasm-pack
npx gulp compile
node

inside of the node REPL, type the following to setup some baseline env:

// we can import parts of nixpkgs,
// going directly to `impure.nix` avoids confrontation with missing nix-version stuff
// we must use an absolute path for the initial file

let wtf = require('wtfnode');
let nixRtFe = await import('./mock-runtime.mjs');
let a = await nixRtFe.import_(path.resolve(process.env.HOME,'devel/nixpkgs/pkgs/top-level/impure.nix'));
let b = await a({localSystem:{system:'x86_64-linux'}});

TODO

• reintroduce laziness (because just using promises results in too many errors)
• nested attrset keys and non-recursive attrsets are implemented suboptimally
• implement missing nix builtins (esp. those marked with TODO:)
  • derivation should create an object with a realise method
• reduce the call stack size and investigate the use of Promise in JS.
• Promise's are incompatible with the current use of force...