hnix

Haskell parser, evaluator and type checker for the Nix language.

Prerequisites

Nix is installed and in your $PATH. This is so that nix-store can be used for interacting with store paths, until hnix-store is ready.

Getting Started

$ git clone --recursive https://github.com/haskell-nix/hnix.git
...
$ cd hnix
$ nix-shell
$ cabal v2-configure --enable-tests
$ cabal v2-build
$ cabal v2-test
# To run all of the tests, which takes up to a minute:
$ env ALL_TESTS=yes cabal v2-test
# To run only specific tests (see `tests/Main.hs` for a list)
$ env NIXPKGS_TESTS=yes PRETTY_TESTS=1 cabal v2-test
$ ./dist/build/hnix/hnix --help

Using the REPL

To enter the hnix REPL use

hnix --repl

To evaluate an expression and make it available in the REPL as the input variable use

hnix --eval -E '(import <nixpkgs> {}).pkgs.hello' --repl

Use the :help command for a list of all available REPL commands.

Building with full debug info

To build hnix for debugging, and with full tracing output and stack traces, use:

$ nix-shell
$ cabal v2-configure --enable-tests --enable-profiling --flags=profiling --flags=tracing
$ cabal v2-build
$ ./dist/build/hnix/hnix -v5 --trace <args> +RTS -xc

Note that this will run quite slowly, but will give the most information as to what might potentially be going wrong during parsing or evaluation.

Building with benchmarks enabled

To build hnix with benchmarks enabled:

$ nix-shell --arg doBenchmarks true
$ cabal v2-configure --enable-tests --enable-benchmarks
$ cabal v2-build
$ cabal v2-bench

Building with profiling enabled

To build hnix with profiling enabled:

$ nix-shell
$ cabal v2-configure --enable-tests --enable-profiling --flags=profiling
$ cabal v2-build
$ ./dist/build/hnix/hnix <args> +RTS -p

Building with GHCJS

From the project root directory, run:

$ NIX_CONF_DIR=$PWD/ghcjs nix-build ghcjs

This will build an hnix library that can be linked to your GHCJS application.

Using the Cachix binary cache

If you're on macOS, you can use the binary cache at Cachix to avoid building the specific dependencies used by hnix. Just use these commands:

$ nix-env -iA cachix -f https://github.com/NixOS/nixpkgs/tarball/db557aab7b690f5e0e3348459f2e4dc8fd0d9298
$ cachix use hnix

How you can help

Issue Tracker Backlog

If you're looking for a way to help out, try taking a look here. When you find an issue that looks interesting to you, comment on the ticket to let others know you're working on it; look for others who might have done the same. You can talk with everyone live on Gitter.

When you're ready to submit a pull request, test it with:

$ git submodule update --init --recursive
$ nix-shell --run "LANGUAGE_TESTS=yes cabal v2-test"

Make sure that all the tests that were passing prior to your PR are still passing afterwards; it's OK if no new tests are passing.

Evaluating Nixpkgs with HNix

Currently the main high-level goal is to be able to evaluate all of nixpkgs. To run this yourself, first build hnix with nix-build, then run the following command:

$ ./result/bin/hnix --eval -E "import <nixpkgs> {}" --find