helix: reenable haskell syntax highlighting support

Haskell syntax highlighting is disabled in `helix-editor` by default.
This is because of an issue compiling tree-sitter-haskell on M1 macs,
as its default compiler doesn't support c++14.
As we're using a nix-derived toolchain, we shouldn't be subject to
this problem.

See [this comment](helix-editor/helix#1384 (comment))
for more info.

pkgs/applications/editors/helix/default.nix

@@ -16,6 +16,10 @@ rustPlatform.buildRustPackage rec {
 
   nativeBuildInputs = [ makeWrapper ];
 
+  patches = [
+    ./patches/reenable-haskell.patch
+  ];
+
   postInstall = ''
     mkdir -p $out/lib
     cp -r runtime $out/lib

pkgs/applications/editors/helix/patches/reenable-haskell.patch

@@ -0,0 +1,13 @@
+diff --git a/helix-syntax/build.rs b/helix-syntax/build.rs
+index 28f85e7..bad1c6b 100644
+--- a/helix-syntax/build.rs
++++ b/helix-syntax/build.rs
+@@ -175,7 +175,7 @@ fn build_dir(dir: &str, language: &str) {
+ fn main() {
+     let ignore = vec![
+         "tree-sitter-typescript".to_string(),
+-        "tree-sitter-haskell".to_string(), // aarch64 failures: https://github.com/tree-sitter/tree-sitter-haskell/issues/34
++        // "tree-sitter-haskell".to_string(), // aarch64 failures: https://github.com/tree-sitter/tree-sitter-haskell/issues/34
+         "tree-sitter-ocaml".to_string(),
+     ];
+     let dirs = collect_tree_sitter_dirs(&ignore).unwrap();