depot/third_party/nixpkgs/doc/languages-frameworks/hare.section.md
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# Hare {#sec-language-hare}
## Building Hare programs with `hareHook` {#ssec-language-hare}
The `hareHook` package sets up the environment for building Hare programs by
doing the following:
1. Setting the `HARECACHE`, `HAREPATH` and `NIX_HAREFLAGS` environment variables;
1. Propagating `harec`, `qbe` and two wrapper scripts for the hare binary.
It is not a function as is the case for some other languages --- *e. g.*, Go or
Rust ---, but a package to be added to `nativeBuildInputs`.
## Attributes of `hareHook` {#hareHook-attributes}
The following attributes are accepted by `hareHook`:
1. `hareBuildType`: Either `release` (default) or `debug`. It controls if the
`-R` flag is added to `NIX_HAREFLAGS`.
## Example for `hareHook` {#ex-hareHook}
```nix
{
hareHook,
lib,
stdenv,
}: stdenv.mkDerivation {
pname = "<name>";
version = "<version>";
src = "<src>";
nativeBuildInputs = [ hareHook ];
meta = {
description = "<description>";
inherit (hareHook) badPlatforms platforms;
};
}
```
## Cross Compilation {#hareHook-cross-compilation}
`hareHook` should handle cross compilation out of the box. This is the main
purpose of `NIX_HAREFLAGS`: In it, the `-a` flag is passed with the architecture
of the `hostPlatform`.
However, manual intervention may be needed when a binary compiled by the build
process must be run for the build to complete --- *e. g.*, when using Hare's
`hare` module for code generation.
In those cases, `hareHook` provides the `hare-native` script, which is a wrapper
around the hare binary for using the native (`buildPlatform`) toolchain.