languages/markdown: add mdformat (#1396)

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

@@ -169,6 +169,8 @@
 - Added [Selenen](https://github.com/kampfkarren/selene) for more diagnostics in
   `languages.lua`.
 
+- Added [`mdformat`](https://mdformat.rtfd.io/) support to `languages.python`.
+
 - Added XML syntax highlighting, LSP support and formatting
 
 - Added [tera](https://keats.github.io/tera/) language support (syntax

modules/plugins/languages/markdown.nix

@@ -5,7 +5,7 @@
   ...
 }: let
   inherit (builtins) attrNames;
-  inherit (lib.meta) getExe;
+  inherit (lib.meta) getExe getExe';
   inherit (lib.modules) mkIf mkMerge;
   inherit (lib.options) mkEnableOption mkOption;
   inherit (lib.types) bool enum listOf str nullOr;
@@ -55,6 +55,14 @@
     prettierd = {
       command = getExe pkgs.prettierd;
     };
+    mdformat = {
+      command = getExe' (pkgs.python313Packages.python.withPackages (p:
+        with p; [
+          mdformat
+          mdformat-gfm
+          mdformat-frontmatter
+        ])) "mdformat";
+    };
   };
   defaultDiagnosticsProvider = ["markdownlint-cli2"];
   diagnosticsProviders = {