darcs: add module

modules/programs/darcs.nix

@@ -0,0 +1,52 @@
+{ config, lib, pkgs, ... }:
+
+with lib;
+
+let
+
+  cfg = config.programs.darcs;
+
+in {
+  meta.maintainers = with maintainers; [ chris-martin ];
+
+  options = {
+    programs.darcs = {
+      enable = mkEnableOption "darcs";
+
+      package = mkPackageOption pkgs "darcs" { };
+
+      author = mkOption {
+        type = types.listOf types.str;
+        default = [ ];
+        example = [ "Fred Bloggs <fred@example.net>" ];
+        description = ''
+          If this list has a single entry, it will be used as the author
+          when you record a patch. If there are multiple entries, Darcs
+          will prompt you to choose one of them.
+        '';
+      };
+
+      boring = mkOption {
+        type = types.listOf types.str;
+        default = [ ];
+        example = [ "^.idea$" ".iml$" "^.stack-work$" ];
+        description = "File patterns to ignore";
+      };
+    };
+  };
+
+  config = mkIf cfg.enable (mkMerge [
+    { home.packages = [ cfg.package ]; }
+
+    (mkIf (cfg.author != [ ]) {
+      home.file.".darcs/author".text =
+        concatMapStrings (x: x + "\n") cfg.author;
+    })
+
+    (mkIf (cfg.boring != [ ]) {
+      home.file.".darcs/boring".text =
+        concatMapStrings (x: x + "\n") cfg.boring;
+    })
+
+  ]);
+}