lib: add concatMap

lib.nix

@@ -13,6 +13,12 @@ rec {
     in
     fold' 0;
 
+  concatMap = op: list:
+    let
+      concat = (a: b: op a + b);
+    in
+    foldr concat "" list;
+
   extractAttrs = attr: list:
     let
       getAttr' = builtins.getAttr attr;
@@ -30,10 +36,5 @@ rec {
     EOF
   '';
 
-  mkLuaRc = contents:
+  mkLuaRc = contents: concatMap mkLuaHeredoc contents;
-    let
-      concat = (a: b: a + b);
-      luaHeredors = builtins.map mkLuaHeredoc contents;
-    in
-    foldr concat "" luaHeredors;
 }