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hnix

	CI

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

Prerequisites

Until hnix-store is ready, nix-store is still used for interacting with the store paths, so Nix is still required installed and available through $PATH.

Getting Started

git clone --recursive https://github.com/haskell-nix/hnix.git
cd hnix
nix-shell
cabal v2-configure --enable-tests
cabal v2-build

Run testing:

Default:
```
cabal v2-test
```
All:
```
env ALL_TESTS=yes cabal v2-test
```

Selected (list of tests is in tests/Main.hs):

env NIXPKGS_TESTS=yes PRETTY_TESTS=1 cabal v2-test

Run built binary with Cabal (-- is for separation between cabal & hnix args):

cabal v2-run hnix -- --help

Using the REPL

Enter REPL:

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
cabal v2-run 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
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
cabal v2-run hnix -- <args> +RTS -p

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

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