languages/haskell.nix: address PR comments

- Rename hls -> haskell-language-server to match the nixpkgs name
- Remove unneeded injection
- Only set lsp filetypes in the language module, not the preset
- Remove unneeded `mkDefault`
- Use `root_markers` instead of yucky inline Lua

docs/manual/release-notes/rl-0.9.md

@@ -204,9 +204,9 @@
 [dathegreat](https://github.com/dathegreat):
 
 - Fixed invalid keys in the haskell-tools configuration
-- Changed the default haskell formatter to
-  [fourmolu](https://github.com/fourmolu/fourmolu), matching the
-  [haskell-tools default](https://github.com/mrcjkb/haskell-tools.nvim/blob/9ea030aa67f3875753e70e1eb59701f7020479a0/lua/haskell-tools/config/internal.lua#L131)
+- Split haskell configuration into `lsp/presets/haskell-language-server.nix` and
+  `languages/haskell.nix`
+- Made the haskell LSP and formatter configurable
 
 [alfarel](https://github.com/alfarelcynthesis):
 

modules/plugins/languages/haskell.nix

@@ -18,9 +18,9 @@
 
   cfg = config.vim.languages.haskell;
 
-  defaultServers = ["hls"];
+  defaultServers = ["haskell-language-server"];
   servers = {
-    hls = {};
+    haskell-language-server = {};
   };
 in {
   options.vim.languages.haskell = {
@@ -84,6 +84,8 @@ in {
       };
     })
 
+    # haskell-tools prefers to manage the lsp directly,
+    # so we only configure the lsp ourselves if haskell-tools is disabled
     (mkIf (cfg.lsp.enable && !cfg.extensions.haskell-tools.enable) {
       vim.lsp = {
         presets = genAttrs cfg.lsp.servers (_: {enable = true;});

modules/plugins/lsp/presets/default.nix

@@ -22,7 +22,7 @@
     ./gopls.nix
     ./harper.nix
     ./helm-ls.nix
-    ./hls.nix
+    ./haskell-language-server.nix
     ./intelephense.nix
     ./jdt-language-server.nix
     ./jinja-lsp.nix

modules/plugins/lsp/presets/haskell-language-server.nix

@@ -0,0 +1,30 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}: let
+  inherit (lib.meta) getExe';
+  inherit (lib.modules) mkIf;
+  inherit (lib.nvim.types) mkLspPresetEnableOption;
+
+  cfg = config.vim.lsp.presets.haskell-language-server;
+in {
+  options.vim.lsp.presets.haskell-language-server = {
+    enable = mkLspPresetEnableOption "haskell-language-server" "Haskell" [];
+  };
+
+  config = mkIf cfg.enable {
+    vim.lsp.servers.haskell-language-server = {
+      enable = true;
+      cmd = [(getExe' pkgs.haskellPackages.haskell-language-server "haskell-language-server-wrapper") "--lsp"];
+      root_markers = ["hie.yaml" "stack.yaml" "cabal.project" "*.cabal" "package.yaml"];
+      settings = {
+        haskell = {
+          formattingProvider = "ormolu";
+          cabalFormattingProvider = "cabal-fmt";
+        };
+      };
+    };
+  };
+}

modules/plugins/lsp/presets/hls.nix

@@ -1,42 +0,0 @@
-{
-  config,
-  lib,
-  pkgs,
-  ...
-}: let
-  inherit (lib.meta) getExe';
-  inherit (lib.modules) mkDefault mkIf;
-  inherit (lib.nvim.types) mkLspPresetEnableOption;
-  inherit (lib.generators) mkLuaInline;
-
-  cfg = config.vim.lsp.presets.hls;
-in {
-  options.vim.lsp.presets.hls = {
-    enable = mkLspPresetEnableOption "hls" "Haskell" [];
-  };
-
-  config = mkIf cfg.enable {
-    vim.lsp.servers.hls = {
-      enable = true;
-      cmd = [(getExe' pkgs.haskellPackages.haskell-language-server "haskell-language-server-wrapper") "--lsp"];
-      filetypes = ["haskell" "lhaskell"];
-      root_dir =
-        mkLuaInline
-        /*
-        lua
-        */
-        ''
-          function(bufnr, on_dir)
-            local fname = vim.api.nvim_buf_get_name(bufnr)
-            on_dir(util.root_pattern('hie.yaml', 'stack.yaml', 'cabal.project', '*.cabal', 'package.yaml')(fname))
-          end
-        '';
-      settings = {
-        haskell = {
-          formattingProvider = mkDefault "ormolu";
-          cabalFormattingProvider = "cabal-fmt";
-        };
-      };
-    };
-  };
-}