remove empty return statement at end of fndef (#20)

moonscript/transform.lua

@@ -1025,12 +1025,18 @@ default_accumulator = function(self, node)
 end
 local implicitly_return
 implicitly_return = function(scope)
+  local is_top = true
   local fn
   fn = function(stm)
     local t = ntype(stm)
     if types.manual_return[t] or not types.is_value(stm) then
-      return stm
+      if is_top and t == "return" and stm[2] == "" then
+        return nil
+      else
+        return stm
+      end
     elseif types.cascading[t] then
+      is_top = false
       return scope.transform.statement(stm, fn)
     else
       if t == "comprehension" and not types.comprehension_has_value(stm) then

moonscript/transform.moon

@@ -528,11 +528,17 @@ default_accumulator = (node) =>
 
 
 implicitly_return = (scope) ->
+  is_top = true
   fn = (stm) ->
     t = ntype stm
     if types.manual_return[t] or not types.is_value stm
-      stm
+      -- remove blank return statement
+      if is_top and t == "return" and stm[2] == ""
+        nil
+      else
+        stm
     elseif types.cascading[t]
+      is_top = false
       scope.transform.statement stm, fn
     else
       if t == "comprehension" and not types.comprehension_has_value stm

tests/outputs/funcs.lua

@@ -94,9 +94,7 @@ _ = function(self, x, y, z)
   end
   self.x, self.z = x, z
 end
-x(function()
-  return 
-end)
+x(function() end)
 y(function()
   return 1
 end)