add dict and nil

flake.nix

@@ -18,6 +18,5 @@
           type = "app";
           program = toString runTests;
         };
-
       });
 }

lib.nix

@@ -1,19 +1,46 @@
 let
-  inherit (builtins) isString isFloat isInt isBool isList concatStringsSep;
+  inherit (builtins) isString isFloat isInt isBool isList isAttrs isNull;
+  inherit (builtins) concatStringsSep filter mapAttrs attrValues;
+
+  mkLuaNil = { _type = "nil"; };
+  isLuaNil = val: isAttrs val && val ? _type && val._type == "nil";
 
   toLua = val:
-    if isList val then toLuaList val
+    if isLuaNil val then "nil"
+    else if isAttrs val then toLuaDict val
+    else if isList val then toLuaList val
     else if isString val then toLuaStr val
     else if isFloat val || isInt val then toString val
     else if isBool val then toLuaBool val
-    else "";
+    else if isNull val then null
+    else null;
 
-  toLuaList = val: "{ ${concatStringsSep ", " (map toLua val)} }";
+  toLuaList = val:
+    wrapObj (excludeNull (map toLua val));
 
-  toLuaStr = val: "'${val}'";
+  toLuaDict = val:
+    let
+      toDictItem = name: value:
+        let luaValue = toLua value;
+        in
+        if isNull luaValue then null
+        else "[${toLuaStr name}] = ${luaValue}";
+
+      dictItems = excludeNull (attrValues (mapAttrs toDictItem val));
+    in
+    wrapObj dictItems;
+
+  excludeNull = val: filter (v: !(isNull v)) val;
+
+  wrapObj = val: "{ ${concatStringsSep ", " val} }";
+
+  toLuaStr = val: "\"${val}\"";
 
   toLuaBool = val: if val then "true" else "false";
+
+
 in
 {
   inherit toLua;
+  inherit mkLuaNil;
 }

lib.test.nix

@@ -2,21 +2,29 @@
 
 let
   nix2lua = import ./lib.nix;
-  inherit (nix2lua) toLua;
+  inherit (nix2lua) toLua mkLuaNil;
 in
 pkgs.lib.runTests {
-  "test returns an empty string" = {
+  "test returns null" = {
     expr = toLua null;
-    expected = "";
+    expected = null;
+  };
+  "test returns nil" = {
+    expr = toLua mkLuaNil;
+    expected = "nil";
   };
   "test returns a lua string" = {
     expr = toLua "hello world";
-    expected = "'hello world'";
+    expected = "\"hello world\"";
   };
   "test returns an integer number" = {
     expr = toLua 10;
     expected = "10";
   };
+  "test returns a negative integer number" = {
+    expr = toLua (-10);
+    expected = "-10";
+  };
   "test returns a float number" = {
     expr = toLua 10.1;
     expected = "10.100000";
@@ -31,6 +39,34 @@ pkgs.lib.runTests {
   };
   "test returns array with all primitive types" = {
     expr = toLua [ "hello" 10 10.1 true ];
-    expected = "{ 'hello', 10, 10.100000, true }";
+    expected = "{ \"hello\", 10, 10.100000, true }";
+  };
+  "test returns array without null values" = {
+    expr = toLua [ null "hello" null 10 null 10.1 null true null ];
+    expected = "{ \"hello\", 10, 10.100000, true }";
+  };
+  "test returns dict" = {
+    expr = toLua {
+      foo = "hello";
+      int = 10;
+      float = 10.1;
+      success = true;
+      fail = false;
+    };
+    expected = "{ [\"fail\"] = false, [\"float\"] = 10.100000, [\"foo\"] = \"hello\", [\"int\"] = 10, [\"success\"] = true }";
+  };
+  "test returns dict without nullable items" = {
+    expr = toLua { foo = "hello"; bar = null; };
+    expected = "{ [\"foo\"] = \"hello\" }";
+  };
+  "test returns recursive dict" = {
+    expr = toLua {
+      first = {
+        second = {
+          last = "hello";
+        };
+      };
+    };
+    expected = "{ [\"first\"] = { [\"second\"] = { [\"last\"] = \"hello\" } } }";
   };
 }