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1# Hare {#sec-language-hare}
2
3## Building Hare programs with `hareHook` {#ssec-language-hare}
4
5The `hareHook` package sets up the environment for building Hare programs by
6doing the following:
7
81. Setting the `HARECACHE`, `HAREPATH` and `NIX_HAREFLAGS` environment variables;
91. Propagating `harec`, `qbe` and two wrapper scripts for the hare binary.
10
11It is not a function as is the case for some other languages --- *e. g.*, Go or
12Rust ---, but a package to be added to `nativeBuildInputs`.
13
14## Attributes of `hareHook` {#hareHook-attributes}
15
16The following attributes are accepted by `hareHook`:
17
181. `hareBuildType`: Either `release` (default) or `debug`. It controls if the
19 `-R` flag is added to `NIX_HAREFLAGS`.
20
21## Example for `hareHook` {#ex-hareHook}
22
23```nix
24{
25 hareHook,
26 lib,
27 stdenv,
28}: stdenv.mkDerivation {
29 pname = "<name>";
30 version = "<version>";
31 src = "<src>";
32
33 nativeBuildInputs = [ hareHook ];
34
35 meta = {
36 description = "<description>";
37 inherit (hareHook) badPlatforms platforms;
38 };
39}
40```
41
42## Cross Compilation {#hareHook-cross-compilation}
43
44`hareHook` should handle cross compilation out of the box. This is the main
45purpose of `NIX_HAREFLAGS`: In it, the `-a` flag is passed with the architecture
46of the `hostPlatform`.
47
48However, manual intervention may be needed when a binary compiled by the build
49process must be run for the build to complete --- *e. g.*, when using Hare's
50`hare` module for code generation.
51
52In those cases, `hareHook` provides the `hare-native` script, which is a wrapper
53around the hare binary for using the native (`buildPlatform`) toolchain.