doc: update readme

README.md

@@ -285,6 +285,38 @@ Add `nix2lua` as input to your `flake.nix`
 > # local function foo(bar) bar.baz() end
 > ```
 
+`return expr`
+
+> Return expression from a function.
+>
+> ```nix
+> toLua (func "foo" ["bar"] (return (pipe1 "bar" "baz"));
+> # function foo(bar) return bar.baz end
+> ```
+>
+> Useful aliases:
+> ```
+> return_void = return null;
+> ```
+
+`ifelse condition trueBody falseBody`
+
+> Make a Lua if else statement.
+>
+> ```nix
+> toLua (ifelse (eq 10 10) (call "print" "yes") (call "print" "no"));
+> # if (10 == 10) print("yes") else print("no") end
+> ```
+
+`if' condition trueBody`
+
+> Make a Lua if statement without else.
+>
+> ```nix
+> toLua (if' (eq 10 10) (call "print" "yes"));
+> # if (10 == 10) print("yes") end
+> ```
+
 # License
 
 GNU General Public License v3.0 or later

lib.nix

@@ -152,8 +152,7 @@ let
   lambda0 = lambda [ ];
 
   return = expr: spaceBetween ([ kw_return expr ]);
-  return_void = return
+  return_void = return null;
-    null;
 
   ifelse = condition: trueBody: falseBody:
     (spaceBetween (concatLists [