syntax for table array iteration

moonscript/compile.lua

@@ -281,16 +281,33 @@ local compiler_index = {
 			and { ("table.insert(tmp, %s)"):format(self:value(exp)) }
 			or { self:stm(exp) }
 
+		self:push()
 		for i = #clauses,1,-1 do
 			local c = clauses[i]
 
 			if "for" == c[1] then
 				local _, names, iter = unpack(c)
-				action = {
-					("for %s in %s do"):format(self:name_list(names), self:value(iter)),
-					action,
-					"end"
-				}
+				if ntype(iter) == "unpack" then
+					iter = iter[2]
+					local items_tmp, index_tmp = self:get_free_name("items"), self:get_free_name("index")
+
+					self:put_name(items_tmp)
+					self:put_name(index_tmp)
+
+					action = {
+						("local %s = %s"):format(items_tmp, self:value(iter)),
+						("for %s=1,#%s do"):format(index_tmp, items_tmp),
+						{("local %s = %s[%s]"):format(self:name_list(names), items_tmp, index_tmp)},
+						action,
+						"end"
+					}
+				else
+					action = {
+						("for %s in %s do"):format(self:name_list(names), self:value(iter)),
+						action,
+						"end"
+					}
+				end
 			elseif "when" == c[1] then
 				local _, when = unpack(c)
 				action = {
@@ -302,6 +319,7 @@ local compiler_index = {
 				error("Unknown clause type :"..tostring(c[1]))
 			end
 		end
+		self:pop()
 
 		if return_value then
 			return self:pretty{

moonscript/parse.lua

@@ -243,12 +243,10 @@ local build_grammar = wrap(function()
 
 		While = key"while" * Exp * key"do"^-1 * Body / mark"while",
 
-		Comprehension = sym"[" * Exp *
-			Ct((key"for" * Ct(NameList) * key"in" * Exp / mark"for") * CompClause^0) *
-			sym"]" / mark"comprehension",
+		Comprehension = sym"[" * Exp * CompInner * sym"]" / mark"comprehension",
 
 		CompInner = Ct(CompFor * CompClause^0),
-		CompFor = key"for" * Ct(NameList) * key"in" * Exp / mark"for",
+		CompFor = key"for" * Ct(NameList) * key"in" * (sym"*" * Exp / mark"unpack" + Exp) / mark"for",
 		CompClause = CompFor + key"when" * Exp / mark"when",
 
 		Assign = Ct(AssignableList) * sym"=" * (Ct(TableBlock + ExpListLow) + If) / mark"assign",

tests/inputs/lists.moon

@@ -39,3 +39,13 @@ x = [x for x in x]
 
 print x,y for x in ipairs{1,2,4} for y in ipairs{1,2,3} when x != 2
 
+double = [x*2 for x in *items]
+
+print x for x in *double
+
+cut = [x for x in *items when x > 3]
+
+hello = [x + y for x in *items for y in *items]
+
+print z for z in *hello
+

tests/outputs/lists.lua

@@ -121,4 +121,47 @@ for x in ipairs({ 1, 2, 4 }) do
       print(x, y)
     end
   end
+end
+local double = (function()
+  local tmp = {}
+  local _items_0 = items
+  for _index_0=1,#_items_0 do
+    local x = _items_0[_index_0]
+    table.insert(tmp, x * 2)
+  end
+  return tmp
+end)()
+local _items_0 = double
+for _index_0=1,#_items_0 do
+  local x = _items_0[_index_0]
+  print(x)
+end
+local cut = (function()
+  local tmp = {}
+  local _items_0 = items
+  for _index_0=1,#_items_0 do
+    local x = _items_0[_index_0]
+    if x > 3 then
+      table.insert(tmp, x)
+    end
+  end
+  return tmp
+end)()
+local hello = (function()
+  local tmp = {}
+  local _items_1 = items
+  for _index_1=1,#_items_1 do
+    local x = _items_1[_index_1]
+    local _items_0 = items
+    for _index_0=1,#_items_0 do
+      local y = _items_0[_index_0]
+      table.insert(tmp, x + y)
+    end
+  end
+  return tmp
+end)()
+local _items_0 = hello
+for _index_0=1,#_items_0 do
+  local z = _items_0[_index_0]
+  print(z)
 end