add dict item

lib.nix

@@ -3,10 +3,21 @@ let
   inherit (builtins) concatStringsSep filter mapAttrs attrValues;
 
   mkLuaNil = { _type = "nil"; };
-  isLuaNil = val: isAttrs val && val ? _type && val._type == "nil";
+  isLuaNil = val: getType val == "nil";
+
+  mkDictItem = name: value: {
+    _type = "dict_item";
+    name = validString name;
+    value = toLua value;
+  };
+  isDictItem = val: getType val == "dict_item";
+  toLuaDictItem = name: value:
+    if isNull value then null
+    else "[${toLuaStr name}] = ${value}";
 
   toLua = val:
     if isLuaNil val then "nil"
+    else if isDictItem val then toLuaDictItem val.name val.value
     else if isAttrs val then toLuaDict val
     else if isList val then toLuaList val
     else if isString val then toLuaStr val
@@ -18,29 +29,24 @@ let
   toLuaList = val:
     wrapObj (excludeNull (map toLua val));
 
-  toLuaDict = val:
-    let
-      toDictItem = name: value:
-        let luaValue = toLua value;
-        in
-        if isNull luaValue then null
-        else "[${toLuaStr name}] = ${luaValue}";
-
-      dictItems = excludeNull (attrValues (mapAttrs toDictItem val));
-    in
-    wrapObj dictItems;
+  toLuaDict = val: toLua (attrValues (mapAttrs mkDictItem val));
 
   excludeNull = val: filter (v: !(isNull v)) val;
 
   wrapObj = val: "{ ${concatStringsSep ", " val} }";
 
-  toLuaStr = val: "\"${val}\"";
+  toLuaStr = val: "\"${validString val}\"";
 
   toLuaBool = val: if val then "true" else "false";
 
+  getType = val: if isAttrs val && val ? _type then val._type else null;
+
+  validString = value:
+    if isString value then value
+    else throw "Value '${toString value}' is not a valid string";
 
 in
 {
   inherit toLua;
-  inherit mkLuaNil;
+  inherit mkLuaNil mkDictItem;
 }

lib.test.nix

@@ -2,7 +2,7 @@
 
 let
   nix2lua = import ./lib.nix;
-  inherit (nix2lua) toLua mkLuaNil;
+  inherit (nix2lua) toLua mkLuaNil mkDictItem;
 in
 pkgs.lib.runTests {
   "test returns null" = {
@@ -69,4 +69,12 @@ pkgs.lib.runTests {
     };
     expected = "{ [\"first\"] = { [\"second\"] = { [\"last\"] = \"hello\" } } }";
   };
+  "test returns array with dict items" = {
+    expr = toLua [
+      "foo"
+      (mkDictItem "foo" "hello")
+      10
+    ];
+    expected = "{ \"foo\", [\"foo\"] = \"hello\", 10 }";
+  };
 }