modules/filetype: add extra filetype detect

modules/filetype.nix

@@ -1,6 +1,17 @@
 { config, lib, ... }:
 
-let cfg = config.filetype; in
+let
+  cfg = config.filetype;
+
+  mkFiletypeDetect = ft: pattern: {
+    "filetype-detect-${ft}" = {
+      event = [ "BufNewFile" "BufRead" ];
+      inherit pattern;
+      command = "setfiletype ${ft}";
+    };
+  };
+in
+
 {
   options.filetype = with lib; with types; {
     enable = mkOption {
@@ -40,7 +51,7 @@ let cfg = config.filetype; in
     };
 
     ignore = mkOption {
-      type = uniq (listOf str);
+      type = extCommas;
       default = [ "Z" "gz" "bz2" "zip" "tgz" ];
       description = ''
         To avoid that certain files are being inspected, the g:ft_ignore_pat variable
@@ -49,10 +60,16 @@ let cfg = config.filetype; in
         `:help filetype-ignore`
       '';
     };
+
     extraIgnore = mkOption {
-      type = uniq (listOf str);
+      type = extCommas;
       default = [ ];
     };
+
+    detect = mkOption {
+      type = attrsOf extCommas;
+      default = { };
+    };
   };
 
   config = {
@@ -62,6 +79,8 @@ let cfg = config.filetype; in
       );
 
     vim.g.ft_ignore_pat = "\\\\.(${lib.concatStringsSep "|" (cfg.ignore ++ cfg.extraIgnore)})$";
+
+    vim.augroup = lib.mkIf (cfg.detect != { }) (lib.mapAttrsToList mkFiletypeDetect cfg.detect);
   };
 
 }