Apply `style.hs` to `reflex` + `reflex-dom`

[ymeister]

Apply style.hs to reflex + reflex-dom

https://github.com/obsidiansystems/style.hs

• Add as a git submodule under dep/

• Symlink fourmolu.yaml and .hlint.yaml to dep/style.hs/{fourmolu.yaml,.hlint.yaml}

• Run ./fourmolu.yaml on source code directories (it's self-executing)

• Run ./.hlint.yaml on source code directories (it's self-executing)

  • Resolve all hlint issues found. If the issue doesn't make sense to change, upstream it to style.hs hlint config and make a PR

• Add check-fourmolu to release.nix. Example:

    check-fourmolu = pkgs.runCommand "check-fourmolu" {
      src = nix-thunk.haskellPackageSource;
      buildInputs = [
        # As with check-hlint, deliberately not given our own `pkgs`, so that CI
        # formats with the same fourmolu as `nix run github:obsidiansystems/style.hs`.
        (import ./dep/style.hs/fourmolu.nix {})
      ];
    } ''
      set -euo pipefail
  
      # --mode check exits non-zero rather than rewriting anything. The wrapper
      # supplies the bundled config, so no --config flag is needed.
      fourmolu --mode check "$src"
  
      touch "$out" # Make the derivation succeed if we get this far
    '';
  
  

• Add check-hlint to release.nix. Example:

    check-hlint = pkgs.runCommand "check-hlint" {
      src = nix-thunk.haskellPackageSource;
      buildInputs = [
        # The shared Obsidian hlint, from the style.hs submodule. The wrapper
        # supplies its own bundled config, so no --hint flag is needed here.
        #
        # Deliberately *not* given our own `pkgs`: style.hs pins the hlint it was
        # written against (3.10), while our nixpkgs has 3.8, and the two disagree
        # about which hints fire. Using its pin keeps CI in step with what
        # `nix run github:obsidiansystems/style.hs#hlint` reports locally.
        (import ./dep/style.hs/hlint.nix {})
      ];
    } ''
      set -euo pipefail
  
      hlint "$src"
  
      touch "$out" # Make the derivation succeed if we get this far
    '';
  
  

• Make sure it is part of CI checks