http2-grpc-haskell

This organization and repository aim at providing unofficial gRPC implementations for Haskell using native libraries.

Context

Haskell is not an officially supported gRPC language. This repository offers a set of libraries that are compatible with gRPC. A main goal of this initiative is that an intermediate Haskell developper should find the packages reasonably easy to install and easy to tinker with.

Repo organization

The code is split in a number of packages following these three ideas:

• share a common types packages
• have server and client-specific packages
• add a serialization-library specific packages

Bazel for building

Drop inside a nix-shell to utilize bazel with all of the necessary (macOS and/or linux) build tooling.

GHC will be provisioned by nix in the bazel workspace bootstrapping.

Bazel targets can be listed with:

bazel query //...

Current build targets of interest include:

• //grpc-types:grpc_types with core grpc-relevant datatypes and typeclass definitions
• //grpc-proto-lens:grpc_proto_lens with proto-lens specific typeclasses and instances
• //grpc-client:grpc_client with client code for making gRPC requests
• //grpc-server:grpc_server with server code for serving gRPC endpoints

you can build all the targets, which cold should take on the order of 5 mins or so, with:

bazel build //...

drop into an individual target GHCi repl session thus (for example):

bazel run //http2-client-grpc:http2_client_grpc@repl

Usage

A basic example end-to-end setup is given in the examples package.

In here you can find a proto spec for a basic unary gRPC method, along with client and server libraries making use of generated haskell proto-lens code.

Specified in the examples BUILD file, you can find a binary demonstrating these library's usage in the build target example_grpc_bin.

You can run the binary from the nix-shell (which requires PORT=3000 on the localhost interface to be free) with:

bazel run //examples:example_grpc_bin

Alternatives

There is a low-level API in the official gRPC repository. There also is a more-complete API which uses a binding to the C-library and which is supported by AwakeSecurity.