Add Dhall support

flake.nix

@@ -59,6 +59,7 @@
                   "**/scratch/text/vale-ignore.txt".packages = { };
                 };
               };
+              dhall.enable = true;
               haskell.enable = true;
               markdown.enable = true;
               nix.enable = true;

languages/dhall/default.nix

@@ -0,0 +1,52 @@
+# SPDX-FileCopyrightText: 2025 Ethan Reece <contact@ethanreece.com>
+#
+# SPDX-License-Identifier: LGPL-3.0-or-later
+
+{ module-name, ... }:
+{ flake-parts-lib, lib, ... }:
+{
+  options.perSystem = flake-parts-lib.mkPerSystemOption (
+    { config, pkgs, ... }:
+    {
+      options.languages.${module-name} = {
+        enable = lib.mkEnableOption "Dhall";
+        package = lib.mkOption {
+          description = ''
+            Package for Dhall.
+          '';
+          type = lib.types.package;
+          default = pkgs.ghc;
+        };
+      };
+      config = lib.mkIf config.languages.${module-name}.enable ({
+        editors.helix.languages = {
+          language = [
+            {
+              name = "dhall";
+              language-servers = [
+                "dhall-lsp-server"
+              ]
+              ++ (lib.optionals config.languages.en-us.enable [ "typos" ]);
+              formatter = {
+                command = "${config.treefmt.build.wrapper}/bin/treefmt";
+                args = [
+                  "--stdin"
+                  "%{buffer_name}"
+                  "--quiet"
+                ];
+              };
+              auto-format = true;
+            }
+          ];
+          language-server.dhall-lsp-server = {
+
+          };
+          language-server.haskell-language-server = {
+            command = "${pkgs.dhall-lsp-server}/bin/dhall-lsp-server";
+          };
+        };
+        treefmt.programs.dhall.enable = true;
+      });
+    }
+  );
+}