Add support for Vala

examples/vala/devenv.nix

@@ -0,0 +1,22 @@
+{ pkgs, ... }:
+
+{
+  packages = with pkgs; [
+    # Check Vala code files for code-style errors
+    vala-lint
+  ];
+
+  languages = {
+    vala = {
+      enable = true;
+      # This is the default package for Vala for the configured channel (see nixpkgs input in devenv.yaml)
+      # It can be configured to use a specific version
+      # Take a look [here](https://search.nixos.org/packages?channel=unstable&from=0&size=50&sort=relevance&type=packages&query=vala) to find out which versions are available
+      package = pkgs.vala;
+    };
+  };
+
+  enterShell = ''
+    echo "This development environment uses $(vala --version)."
+  '';
+}

examples/vala/devenv.yaml

@@ -0,0 +1,3 @@
+inputs:
+  nixpkgs:
+    url: github:NixOS/nixpkgs/nixpkgs-unstable

src/modules/languages/vala.nix

@@ -0,0 +1,24 @@
+{ pkgs, config, lib, ... }:
+
+let
+  cfg = config.languages.vala;
+in
+{
+  options.languages.vala = {
+    enable = lib.mkEnableOption "tools for Vala development";
+
+    package = lib.mkOption {
+      type = lib.types.package;
+      default = pkgs.vala;
+      defaultText = lib.literalExpression "pkgs.vala";
+      description = "The Vala package to use.";
+      example = lib.literalExpression "pkgs.vala_0_54";
+    };
+  };
+
+  config = lib.mkIf cfg.enable {
+    packages = [
+      cfg.package
+    ];
+  };
+}