8 files changed, 61 insertions, 15 deletions

diff --git a/doc/docs/doc/README.md b/doc/docs/doc/README.md
index 502f7b6..4a408fe 100755
--- a/doc/docs/doc/README.md
+++ b/doc/docs/doc/README.md
@@ -1925,22 +1925,22 @@ x * 2
 </pre>
 </YueDisplay>
 
-If you wish to have further code after your backcalls, you can set them aside with a do statement.
+If you wish to have further code after your backcalls, you can set them aside with a do statement. And the parentheses can be omitted with non-fat arrow functions.
 
 ```moonscript
 result, msg = do
-  (data) <- readAsync "filename.txt"
+  data <- readAsync "filename.txt"
   print data
-  (info) <- processAsync data
+  info <- processAsync data
   check info
 print result, msg
 ```
 <YueDisplay>
 <pre>
 result, msg = do
-  (data) <- readAsync "filename.txt"
+  data <- readAsync "filename.txt"
   print data
-  (info) <- processAsync data
+  info <- processAsync data
   check info
 print result, msg
 </pre>
diff --git a/doc/docs/zh/doc/README.md b/doc/docs/zh/doc/README.md
index e5efe3b..d7b8361 100755
--- a/doc/docs/zh/doc/README.md
+++ b/doc/docs/zh/doc/README.md
@@ -1886,22 +1886,22 @@ x * 2
 </pre>
 </YueDisplay>
 
-如果你希望在反向回调处理后继续编写更多其它的代码，你可以使用do语句将不归属反向回调的代码分开。
+如果你希望在反向回调处理后继续编写更多其它的代码，可以使用 do 语句将不属于反向回调的代码分隔开。对于非粗箭头函数的反向回调，回调返回值的括号也是可以省略的。
 
 ```moonscript
 result, msg = do
-  (data) <- readAsync "文件名.txt"
+  data <- readAsync "文件名.txt"
   print data
-  (info) <- processAsync data
+  info <- processAsync data
   check info
 print result, msg
 ```
 <YueDisplay>
 <pre>
 result, msg = do
-  (data) <- readAsync "文件名.txt"
+  data <- readAsync "文件名.txt"
   print data
-  (info) <- processAsync data
+  info <- processAsync data
   check info
 print result, msg
 </pre>
diff --git a/spec/inputs/backcall.yue b/spec/inputs/backcall.yue
index 8aadc71..e6b8c21 100644
--- a/spec/inputs/backcall.yue
+++ b/spec/inputs/backcall.yue
@@ -13,9 +13,9 @@ do
         x > 2
 
 do
-        (data) <- http?.get "ajaxtest"
+        data <- http?.get "ajaxtest"
         body[".result"]\html data
-        (processed) <- http.post "ajaxprocess", data
+        processed <- http.post "ajaxprocess", data
         body[".result"]\append processed
         <- setTimeout 1000
         print "done"
diff --git a/src/yuescript/yue_ast.cpp b/src/yuescript/yue_ast.cpp
index 56e3447..fdb1d20 100644
--- a/src/yuescript/yue_ast.cpp
+++ b/src/yuescript/yue_ast.cpp
@@ -331,6 +331,12 @@ std::string Backcall_t::to_string(void* ud) const {
         temp.emplace_back(value->to_string(ud));
         return join(temp, " "sv);
 }
+std::string SubBackcall_t::to_string(void* ud) const {
+        str_list temp;
+        temp.emplace_back(arrow->to_string(ud));
+        temp.emplace_back(value->to_string(ud));
+        return join(temp, " "sv);
+}
 std::string PipeBody_t::to_string(void* ud) const {
         auto info = reinterpret_cast<YueFormat*>(ud);
         str_list temp;
diff --git a/src/yuescript/yue_ast.h b/src/yuescript/yue_ast.h
index 8501a19..0c15fac 100644
--- a/src/yuescript/yue_ast.h
+++ b/src/yuescript/yue_ast.h
@@ -841,9 +841,15 @@ AST_NODE(UnaryExp)
         AST_MEMBER(UnaryExp, &ops, &expos, &inExp)
 AST_END(UnaryExp)
 
+AST_NODE(SubBackcall)
+        ast_ptr<true, FnArrowBack_t> arrow;
+        ast_ptr<true, ChainValue_t> value;
+        AST_MEMBER(SubBackcall, &arrow, &value)
+AST_END(SubBackcall)
+
 AST_NODE(ExpListAssign)
         ast_ptr<true, ExpList_t> expList;
-        ast_sel<false, Update_t, Assign_t> action;
+        ast_sel<false, Update_t, Assign_t, SubBackcall_t> action;
         AST_MEMBER(ExpListAssign, &expList, &action)
 AST_END(ExpListAssign)
 
diff --git a/src/yuescript/yue_compiler.cpp b/src/yuescript/yue_compiler.cpp
index 5cd2804..60ed7ac 100644
--- a/src/yuescript/yue_compiler.cpp
+++ b/src/yuescript/yue_compiler.cpp
@@ -78,7 +78,7 @@ static std::unordered_set<std::string> Metamethods = {
         "close"s // Lua 5.4
 };
 
-const std::string_view version = "0.28.1"sv;
+const std::string_view version = "0.28.2"sv;
 const std::string_view extension = "yue"sv;
 
 class CompileError : public std::logic_error {
@@ -4878,6 +4878,38 @@ private:
                                 newBlock->statements.push_back(toAst<Statement_t>("if "s + okVar + " then return ... else error ..."s, x));
                                 transformBlock(newBlock, out, usage, assignList, isRoot);
                                 return;
+                        } else if (auto expListAssign = stmt->content.as<ExpListAssign_t>();
+                                expListAssign && expListAssign->action && expListAssign->action.is<SubBackcall_t>()) {
+                                auto x = *nodes.begin();
+                                auto newBlock = x->new_ptr<Block_t>();
+                                if (it != nodes.begin()) {
+                                        for (auto i = nodes.begin(); i != it; ++i) {
+                                                newBlock->statements.push_back(*i);
+                                        }
+                                }
+                                auto doBackcall = static_cast<SubBackcall_t*>(expListAssign->action.get());
+                                auto backcall = expListAssign->new_ptr<Backcall_t>();
+                                auto argsDef = backcall->new_ptr<FnArgsDef_t>();
+                                try {
+                                        auto defList = toAst<FnArgDefList_t>(YueFormat{}.toString(expListAssign->expList), expListAssign->expList);
+                                        argsDef->defList.set(defList);
+                                } catch (const std::exception&) {
+                                        throw CompileError("backcall syntax error", backcall);
+                                }
+                                backcall->argsDef.set(argsDef);
+                                backcall->arrow.set(doBackcall->arrow);
+                                backcall->value.set(doBackcall->value);
+                                auto newStmt = backcall->new_ptr<Statement_t>();
+                                newStmt->content.set(backcall);
+                                newStmt->comments.dup(stmt->comments);
+                                newStmt->appendix.set(stmt->appendix);
+                                newBlock->statements.push_back(newStmt);
+                                auto ait = it;
+                                for (auto i = ++ait; i != nodes.end(); ++i) {
+                                        newBlock->statements.push_back(*i);
+                                }
+                                transformBlock(newBlock, out, usage, assignList, isRoot);
+                                return;
                         }
                         if (auto local = stmt->content.as<Local_t>()) {
                                 if (!local->collected) {
diff --git a/src/yuescript/yue_parser.cpp b/src/yuescript/yue_parser.cpp
index 045e2c7..cd1fd48 100644
--- a/src/yuescript/yue_parser.cpp
+++ b/src/yuescript/yue_parser.cpp
@@ -889,6 +889,7 @@ YueParser::YueParser() {
 
         FnArrowBack = '<' >> set("-=");
         Backcall = -(FnArgsDef >> space) >> FnArrowBack >> space >> ChainValue;
+        SubBackcall = FnArrowBack >> space >> ChainValue;
 
         PipeBody = Seperator >>
                 pipe_operator >> space >> UnaryExp >>
@@ -946,7 +947,7 @@ YueParser::YueParser() {
                 UnaryValue | TblComprehension | Comprehension |
                 FunLit | Num | VarArg;
 
-        ExpListAssign = ExpList >> -(space >> (Update | Assign)) >> not_(space >> '=');
+        ExpListAssign = ExpList >> -(space >> (Update | Assign | SubBackcall)) >> not_(space >> '=');
 
         IfLine = IfType >> space >> IfCond;
         WhileLine = WhileType >> space >> Exp;
diff --git a/src/yuescript/yue_parser.h b/src/yuescript/yue_parser.h
index 63afcb9..4488685 100644
--- a/src/yuescript/yue_parser.h
+++ b/src/yuescript/yue_parser.h
@@ -321,6 +321,7 @@ private:
         AST_RULE(ShortTabAppending);
         AST_RULE(FnArrowBack);
         AST_RULE(Backcall);
+        AST_RULE(SubBackcall);
         AST_RULE(PipeBody);
         AST_RULE(ExpListLow);
         AST_RULE(ExpList);