added go, zig, and ruby, as well as environment

modules/dev/go.nix

@@ -0,0 +1,45 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+let
+  packages = builtins.attrValues {
+    inherit (pkgs)
+      go # Go compiler and core toolchain
+      gocode-gomod # Code completion for Go (modern fork of gocode)
+      gotools # Contains godoc, gorename, goimports, etc.
+      gore # Go REPL
+      gotests # Generate Go tests from function signatures
+      gomodifytags # Struct tag manipulation
+      golangci-lint # Linter aggregation
+      ;
+  };
+  GOPATH = "\${XDG_DATA_HOME}/go";
+in
+{
+  options = {
+    my.dev.go.enable = lib.mkEnableOption "Install Go tooling globally";
+    devShells.go = lib.mkOption {
+      type = lib.types.package;
+      default = pkgs.mkShell {
+        inherit packages GOPATH;
+        name = "go-dev-shell";
+        shellHook = ''
+          echo "🐹 Go dev environment"
+        '';
+      };
+      description = "Go development shell with Emacs tooling, REPL, formatter, and linter";
+    };
+  };
+
+  config = lib.mkMerge [
+    {
+      environment.variables = { inherit GOPATH; };
+    }
+    (lib.mkIf config.my.dev.go.enable {
+      users.users.jawz = { inherit packages; };
+    })
+  ];
+}