assignable if, exp list as statement, ; as value separator

moonscript/compile.lua

@@ -44,7 +44,10 @@ local moonlib = {
 }
 
 -- these are always expressions, never statements, must be sent into temp variable
-local must_return = data.Set{ 'parens', 'exp', 'value', 'string', 'table', 'fndef' }
+local must_return = data.Set{ 'parens', 'exp', 'value', 'string', 'table', 'fndef', 'explist' }
+
+-- these can't return a value, and must be munged
+local block_statements = data.Set{ 'if' }
 
 -- make sure there are no block levels statements in expression
 local function validate_expression(block)
@@ -324,7 +327,7 @@ local compiler_index = {
 		local len = #node
 		for i=1,len do
 			local ln = node[i]
-			local value = self:stm(ln, return_value and i == len)
+			local value = self:stm(ln, i == len and return_value)
 			if type(value) == "table" then
 				for _, v in ipairs(value) do
 					table.insert(lines, v)
@@ -384,7 +387,6 @@ local compiler_index = {
 
 	assign = function(self, node)
 		local _, names, values = unpack(node)
-		local assigns, current = {}, nil
 
 		-- declare undeclared names
 		local undeclared_names = {}
@@ -395,19 +397,26 @@ local compiler_index = {
 			end
 		end
 
+		local compact = not block_statements[ntype(values)] and #undeclared_names == #names
+
 		local lines = {}
 		local num_undeclared = #undeclared_names
-		if num_undeclared > 0 and num_undeclared ~= #names then
+		if num_undeclared > 0 and not compact then
 			table.insert(lines, "local "..table.concat(undeclared_names, ", "))
 		end
 
-		local ln = self:name_list(names)..  " = "..table.concat(self:values(values), ", ")
+		if block_statements[ntype(values)] then
+			table.insert(lines, self:stm(values, self:name_list(names)))
+		else
+			local ln = self:name_list(names).." = "..table.concat(self:values(values), ", ")
 
-		if num_undeclared == #names then
+			if compact then
 				ln = "local "..ln
 			end
 
 			table.insert(lines, ln)
+		end
+
 		return self:pretty(lines)
 	end,
 
@@ -432,6 +441,14 @@ local compiler_index = {
 		return delim..inner..(delim_end or delim)
 	end,
 
+	explist = function(self, node)
+		local values = {}
+		for i=2,#node do
+			table.insert(values, self:value(node[i]))
+		end
+		return table.concat(values, ", ")
+	end,
+
 	value = function(self, node, return_value, ...)
 		if return_value == nil then return_value = true end
 
@@ -452,7 +469,12 @@ local compiler_index = {
 
         if must_return[ntype(node)] then
 			if return_value then
-				return "return "..value
+				local return_to = "return"
+				if type(return_value) == "string" then
+					return_to = return_value.." ="
+				end
+
+				return return_to.." "..value
 			else
 				return self:value({"assign", {"_"}, {value}}, false)
 			end

moonscript/parse.lua

@@ -218,7 +218,7 @@ local build_grammar = wrap(function()
 		Block = Ct(Line * (Break^1 * Line)^0),
 		Line = Cmt(Indent, check_indent) * Statement + _Space * Comment,
 
-		Statement = (Import + If + While + Exp * Space) * (
+		Statement = (Import + If + While + Ct(ExpList) / flatten_or_mark"explist" * Space) * (
 				-- statement decorators
 				key"if" * Exp * (key"else" * Exp)^-1 * Space / mark"if" +
 				CompInner / mark"comprehension"
@@ -249,7 +249,7 @@ local build_grammar = wrap(function()
 		CompFor = key"for" * Ct(NameList) * key"in" * Exp / mark"for",
 		CompClause = CompFor + key"when" * Exp / mark"when",
 
-		Assign = Ct(AssignableList) * sym"=" * Ct(TableBlock + ExpList) / mark"assign",
+		Assign = Ct(AssignableList) * sym"=" * (Ct(TableBlock + ExpListLow) + If) / mark"assign",
 
 		-- we can ignore precedence for now
 		OtherOps = op"or" + op"and" + op"<=" + op">=" + op"~=" + op"!=" + op"==" + op".." + op"<" + op">",
@@ -324,7 +324,8 @@ local build_grammar = wrap(function()
 			(Body + Ct"") / mark"fndef",
 
 		NameList = Name * (sym"," * Name)^0,
-		ExpList = Exp * (sym"," * Exp)^0
+		ExpList = Exp * (sym"," * Exp)^0,
+		ExpListLow = Exp * ((sym"," + sym";") * Exp)^0,
 	}
 
 	return {

test.lua

@@ -50,13 +50,16 @@ local function run_file(name, benchmark)
 	if benchmark then parse_time = gettime() - start_parse end
 
 	if not tree then
-		error("Compile error in "..name.."\n"..err)
+		error("Parse error in "..name.."\n"..err)
 	end
 
 	local start_compile
 	if benchmark then start_compile = gettime() end
 
-	local code = compile.tree(tree)
+	local success, code = pcall(compile.tree, tree)
+	if not success then
+		error("Compile error in"..name..":\n"..code)
+	end
 
 	if benchmark then
 		local compile_time = gettime() - start_compile

tests/inputs/assign.moon

@@ -14,3 +14,17 @@
 
 joop = 2345
 
+a, b = if hello
+  "hello"
+else
+  "nothing", "yeah"
+
+
+a, b = if hello
+  if yeah then "one", "two" else "mmhh"
+else
+  print "the other"
+  "nothing", "yeah"
+
+
+

tests/inputs/syntax.moon

@@ -26,7 +26,7 @@ a, bunch, go, here = another, world
 func arg1, arg2, another, arg3
 
 here, we = () ->, yeah
-the, different = () -> approach, yeah
+the, different = () -> approach; yeah
 
 dad()
 dad(lord)
@@ -132,4 +132,7 @@ y = #"hello"
 
 x = #{#{},#{1},#{1,2}}
 
+hello, world
+
+
 

tests/outputs/assign.lua

@@ -11,3 +11,19 @@ local _ = function()
   end
 end
 local joop = 2345
+local a, b
+if hello then
+  a, b = "hello"
+else
+  a, b = "nothing", "yeah"
+end
+if hello then
+  if yeah then
+    a, b = "one", "two"
+  else
+    a, b = "mmhh"
+  end
+else
+  print("the other")
+  a, b = "nothing", "yeah"
+end

tests/outputs/syntax.lua

@@ -87,3 +87,4 @@ x = not true
 local y = not (5 + 5)
 y = #"hello"
 x = #{ #{  }, #{ 1 }, #{ 1, 2 } }
+_ = hello, world