diff --git a/src/codeobject.h b/src/codeobject.h
index b742dba6..d8552f82 100644
--- a/src/codeobject.h
+++ b/src/codeobject.h
@@ -39,6 +39,9 @@ enum CodeBlockType {
     TRY_EXCEPT,
 };
 
+#define BC_NOARG       -1
+#define BC_KEEPLINE     -1
+
 struct CodeBlock {
     CodeBlockType type;
     int parent;         // parent index in blocks
@@ -68,27 +71,6 @@ struct CodeObject {
 
     void optimize(VM* vm);
 
-    bool add_label(StrName label){
-        if(labels.count(label)) return false;
-        labels[label] = codes.size();
-        return true;
-    }
-
-    int add_name(StrName name, NameScope scope){
-        if(scope == NAME_LOCAL && global_names.count(name)) scope = NAME_GLOBAL;
-        auto p = std::make_pair(name, scope);
-        for(int i=0; i<names.size(); i++){
-            if(names[i] == p) return i;
-        }
-        names.push_back(p);
-        return names.size() - 1;
-    }
-
-    int add_const(PyObject* v){
-        consts.push_back(v);
-        return consts.size() - 1;
-    }
-
     void _mark() const {
         for(PyObject* v : consts) OBJ_MARK(v);
     }
diff --git a/src/common.h b/src/common.h
index 9ca65136..2ae87052 100644
--- a/src/common.h
+++ b/src/common.h
@@ -117,7 +117,7 @@ public:
 	const std::vector<T>& data() const { return vec; }
 };
 
-struct Expression;
-typedef std::unique_ptr<Expression> Expression_;
+struct Expr;
+typedef std::unique_ptr<Expr> Expr_;
 
 } // namespace pkpy
\ No newline at end of file
diff --git a/src/compiler.h b/src/compiler.h
index bc58348f..57d204a8 100644
--- a/src/compiler.h
+++ b/src/compiler.h
@@ -20,41 +20,6 @@ struct PrattRule{
     Precedence precedence;
 };
 
-struct CodeEmitContext{
-    CodeObject_ co;
-    stack<Expression_> s_expr;
-
-    CodeEmitContext(CodeObject_ co): co(co) {}
-
-    int curr_block_i = 0;
-    bool is_compiling_class = false;
-
-    bool is_curr_block_loop() const {
-        return co->blocks[curr_block_i].type == FOR_LOOP || co->blocks[curr_block_i].type == WHILE_LOOP;
-    }
-
-    void enter_block(CodeBlockType type){
-        co->blocks.push_back(CodeBlock{
-            type, curr_block_i, (int)co->codes.size()
-        });
-        curr_block_i = co->blocks.size()-1;
-    }
-
-    void exit_block(){
-        co->blocks[curr_block_i].end = co->codes.size();
-        curr_block_i = co->blocks[curr_block_i].parent;
-        if(curr_block_i < 0) UNREACHABLE();
-    }
-
-    // clear the expression stack and generate bytecode
-    void emit_expr(){
-        if(s_expr.size() != 1) UNREACHABLE();
-        Expression_ expr = s_expr.popx();
-        // emit
-        // ...
-    }
-};
-
 class Compiler {
     std::unique_ptr<Lexer> lexer;
     stack<CodeEmitContext> contexts;
@@ -70,7 +35,7 @@ class Compiler {
     template<typename... Args>
     CodeObject_ push_context(Args&&... args){
         CodeObject_ co = make_sp<CodeObject>(std::forward<Args>(args)...);
-        contexts.push(CodeEmitContext(co));
+        contexts.push(CodeEmitContext(vm, co));
         return co;
     }
 
@@ -117,30 +82,29 @@ public:
         rules[TK("and") ] =     { nullptr,               METHOD(exprAnd),            PREC_LOGICAL_AND };
         rules[TK("or")] =       { nullptr,               METHOD(exprOr),             PREC_LOGICAL_OR };
         rules[TK("not")] =      { METHOD(exprNot),       nullptr,                    PREC_LOGICAL_NOT };
-        rules[TK("True")] =     { METHOD(exprValue),     NO_INFIX };
-        rules[TK("False")] =    { METHOD(exprValue),     NO_INFIX };
+        rules[TK("True")] =     { METHOD(exprLiteral0),     NO_INFIX };
+        rules[TK("False")] =    { METHOD(exprLiteral0),     NO_INFIX };
+        rules[TK("None")] =     { METHOD(exprLiteral0),     NO_INFIX };
+        rules[TK("...")] =      { METHOD(exprLiteral0),     NO_INFIX };
         rules[TK("lambda")] =   { METHOD(exprLambda),    NO_INFIX };
-        rules[TK("None")] =     { METHOD(exprValue),     NO_INFIX };
-        rules[TK("...")] =      { METHOD(exprValue),     NO_INFIX };
         rules[TK("@id")] =      { METHOD(exprName),      NO_INFIX };
         rules[TK("@num")] =     { METHOD(exprLiteral),   NO_INFIX };
         rules[TK("@str")] =     { METHOD(exprLiteral),   NO_INFIX };
         rules[TK("@fstr")] =    { METHOD(exprFString),   NO_INFIX };
         rules[TK("?")] =        { nullptr,               METHOD(exprTernary),        PREC_TERNARY };
         rules[TK("=")] =        { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK("+=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK("-=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK("*=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK("/=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK("//=")] =      { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK("%=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK("&=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK("|=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK("^=")] =       { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK(">>=")] =      { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK("<<=")] =      { nullptr,               METHOD(exprAssign),         PREC_ASSIGNMENT };
-        rules[TK(",")] =        { nullptr,               METHOD(exprComma),          PREC_COMMA };
-        rules[TK(":")] =        { nullptr,               METHOD(exprSlice),          PREC_SLICE };
+        rules[TK("+=")] =       { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK("-=")] =       { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK("*=")] =       { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK("/=")] =       { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK("//=")] =      { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK("%=")] =       { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK("&=")] =       { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK("|=")] =       { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK("^=")] =       { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK(">>=")] =      { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK("<<=")] =      { nullptr,               METHOD(exprInplaceAssign),         PREC_ASSIGNMENT };
+        rules[TK(",")] =        { nullptr,               METHOD(exprTuple),          PREC_TUPLE };
         rules[TK("<<")] =       { nullptr,               METHOD(exprBinaryOp),       PREC_BITWISE_SHIFT };
         rules[TK(">>")] =       { nullptr,               METHOD(exprBinaryOp),       PREC_BITWISE_SHIFT };
         rules[TK("&")] =        { nullptr,               METHOD(exprBinaryOp),       PREC_BITWISE_AND };
@@ -150,7 +114,7 @@ public:
 #undef NO_INFIX
 
 #define EXPR() parse_expression(PREC_TERNARY)             // no '=' and ',' just a simple expression
-#define EXPR_TUPLE() parse_expression(PREC_COMMA)         // no '=', but ',' is allowed
+#define EXPR_TUPLE() parse_expression(PREC_TUPLE)         // no '=', but ',' is allowed
 #define EXPR_ANY() parse_expression(PREC_ASSIGNMENT)
     }
 
@@ -201,96 +165,55 @@ private:
         if (!match_end_stmt()) SyntaxError("expected statement end");
     }
 
-    PyObject* get_value(const Token& token) {
-        switch (token.type) {
-            case TK("@num"):
-                if(std::holds_alternative<i64>(token.value)) return VAR(std::get<i64>(token.value));
-                if(std::holds_alternative<f64>(token.value)) return VAR(std::get<f64>(token.value));
-                UNREACHABLE();
-            case TK("@str"): case TK("@fstr"):
-                return VAR(std::get<Str>(token.value));
-            default: throw std::runtime_error(Str("invalid token type: ") + TK_STR(token.type));
-        }
-    }
-
     void exprLiteral(){
         ctx()->s_expr.push(
-            std::make_unique<LiteralExpr>(prev().value)
+            expr_prev_line<LiteralExpr>(prev().value)
         );
-        // PyObject* value = get_value(prev());
-        // int index = co()->add_const(value);
-        // emit(OP_LOAD_CONST, index);
     }
 
     void exprFString(){
         ctx()->s_expr.push(
-            std::make_unique<FStringExpr>(std::get<Str>(prev().value))
+            expr_prev_line<FStringExpr>(std::get<Str>(prev().value))
         );
-        // static const std::regex pattern(R"(\{(.*?)\})");
-        // PyObject* value = get_value(prev());
-        // Str s = CAST(Str, value);
-        // std::sregex_iterator begin(s.begin(), s.end(), pattern);
-        // std::sregex_iterator end;
-        // int size = 0;
-        // int i = 0;
-        // for(auto it = begin; it != end; it++) {
-        //     std::smatch m = *it;
-        //     if (i < m.position()) {
-        //         std::string literal = s.substr(i, m.position() - i);
-        //         emit(OP_LOAD_CONST, co()->add_const(VAR(literal)));
-        //         size++;
-        //     }
-        //     emit(OP_LOAD_EVAL_FN);
-        //     emit(OP_LOAD_CONST, co()->add_const(VAR(m[1].str())));
-        //     emit(OP_CALL, 1);
-        //     size++;
-        //     i = (int)(m.position() + m.length());
-        // }
-        // if (i < s.size()) {
-        //     std::string literal = s.substr(i, s.size() - i);
-        //     emit(OP_LOAD_CONST, co()->add_const(VAR(literal)));
-        //     size++;
-        // }
-        // emit(OP_BUILD_STRING, size);
     }
 
-    void emit_expr(){}
+    template <typename T, typename... Args>
+    std::unique_ptr<T> expr_prev_line(Args&&... args) {
+        std::unique_ptr<T> expr = std::make_unique<T>(std::forward<Args>(args)...);
+        expr->line = prev().line;
+        return expr;
+    }
 
     void exprLambda(){
-        Function func;
-        func.name = "<lambda>";
+        auto e = expr_prev_line<LambdaExpr>();
+        e->func.name = "<lambda>";
+        e->scope = name_scope();
         if(!match(TK(":"))){
-            _compile_f_args(func, false);
+            _compile_f_args(e->func, false);
             consume(TK(":"));
         }
-        func.code = push_context(lexer->src, func.name.str());
+        e->func.code = push_context(lexer->src, "<lambda>");
         EXPR();
-        emit_expr();
-        emit(OP_RETURN_VALUE);
+        ctx()->emit(OP_RETURN_VALUE, BC_NOARG, BC_KEEPLINE);
         pop_context();
+        ctx()->s_expr.push(std::move(e));
+    }
 
-        ctx()->s_expr.push(
-            std::make_unique<LambdaExpr>(std::move(func), name_scope())
-        );
-
-        // emit(OP_LOAD_FUNCTION, co()->add_const(VAR(func)));
-        // if(name_scope() == NAME_LOCAL) emit(OP_SETUP_CLOSURE);
+    void exprInplaceAssign(){
+        auto e = expr_prev_line<InplaceAssignExpr>();
+        e->op = prev().type;
+        e->lhs = ctx()->s_expr.popx();
+        EXPR_TUPLE();
+        e->rhs = ctx()->s_expr.popx();
+        ctx()->s_expr.push(std::move(e));
     }
 
     void exprAssign(){
-        Expression_ lhs = ctx()->s_expr.popx();
-        TokenIndex op = prev().type;
+        auto e = expr_prev_line<AssignExpr>();
+        e->lhs = ctx()->s_expr.popx();
         EXPR_TUPLE();
-        if(op == TK("=")){
-            ctx()->s_expr.push(
-                std::make_unique<AssignExpr>(std::move(lhs), ctx()->s_expr.popx())
-            );
-        }else{
-            // += -= ...
-            ctx()->s_expr.push(
-                std::make_unique<InplaceAssignExpr>(op, std::move(lhs), ctx()->s_expr.popx())
-            );
-        }
+        e->rhs = ctx()->s_expr.popx();
+        ctx()->s_expr.push(std::move(e));
 
         // if(co()->codes.empty()) UNREACHABLE();
         // bool is_load_name_ref = co()->codes.back().op == OP_LOAD_NAME_REF;
@@ -341,123 +264,73 @@ private:
         // co()->_rvalue -= 1;
     }
 
-    void exprSlice(){
-    }
-
-    void exprComma(){
-        int size = 1;       // an expr is in the stack now
+    void exprTuple(){
+        auto e = expr_prev_line<TupleExpr>();
         do {
             EXPR();         // NOTE: "1," will fail, "1,2" will be ok
-            size++;
+            e->items.push_back(ctx()->s_expr.popx());
         } while(match(TK(",")));
-        std::vector<Expression_> items(size);
-        for(int i=size-1; i>=0; i--) items[i] = ctx()->s_expr.popx();
-        ctx()->s_expr.push(
-            std::make_unique<TupleExpr>(std::move(items))
-        );
-        // emit(co()->_rvalue ? OP_BUILD_TUPLE : OP_BUILD_TUPLE_REF, size);
+        ctx()->s_expr.push(std::move(e));
     }
 
     void exprOr(){
-        Expression_ lhs = ctx()->s_expr.popx();
-        parse_expression(PREC_LOGICAL_OR);
-        ctx()->s_expr.push(
-            std::make_unique<OrExpr>(std::move(lhs), ctx()->s_expr.popx())
-        );
-
-        // int patch = emit(OP_JUMP_IF_TRUE_OR_POP);
-        // parse_expression(PREC_LOGICAL_OR);
-        // patch_jump(patch);
+        auto e = expr_prev_line<OrExpr>();
+        e->lhs = ctx()->s_expr.popx();
+        parse_expression(PREC_LOGICAL_OR + 1);
+        e->rhs = ctx()->s_expr.popx();
+        ctx()->s_expr.push(std::move(e));
     }
 
     void exprAnd(){
-        Expression_ lhs = ctx()->s_expr.popx();
-        parse_expression(PREC_LOGICAL_AND);
-        ctx()->s_expr.push(
-            std::make_unique<AndExpr>(std::move(lhs), ctx()->s_expr.popx())
-        );
-        // int patch = emit(OP_JUMP_IF_FALSE_OR_POP);
-        // parse_expression(PREC_LOGICAL_AND);
-        // patch_jump(patch);
+        auto e = expr_prev_line<OrExpr>();
+        e->lhs = ctx()->s_expr.popx();
+        parse_expression(PREC_LOGICAL_AND + 1);
+        e->rhs = ctx()->s_expr.popx();
+        ctx()->s_expr.push(std::move(e));
     }
 
     void exprTernary(){
-        Expression_ cond = ctx()->s_expr.popx();
+        auto e = expr_prev_line<TernaryExpr>();
+        e->cond = ctx()->s_expr.popx();
         EXPR();         // if true
-        Expression_ true_expr = ctx()->s_expr.popx();
+        e->true_expr = ctx()->s_expr.popx();
         consume(TK(":"));
         EXPR();         // if false
-        Expression_ false_expr = ctx()->s_expr.popx();
-        ctx()->s_expr.push(
-            std::make_unique<TernaryExpr>(std::move(cond), std::move(true_expr), std::move(false_expr))
-        );
-        // int patch = emit(OP_POP_JUMP_IF_FALSE);
-        // EXPR();         // if true
-        // int patch2 = emit(OP_JUMP_ABSOLUTE);
-        // consume(TK(":"));
-        // patch_jump(patch);
-        // EXPR();         // if false
-        // patch_jump(patch2);
+        e->false_expr = ctx()->s_expr.popx();
+        ctx()->s_expr.push(std::move(e));
     }
 
     void exprBinaryOp(){
-        TokenIndex op = prev().type;
-        Expression_ lhs = ctx()->s_expr.popx();
-        parse_expression((Precedence)(rules[op].precedence + 1));
-        ctx()->s_expr.push(
-            std::make_unique<BinaryExpr>(op, std::move(lhs), ctx()->s_expr.popx())
-        );
-        // switch (op) {
-        //     case TK("+"):   emit(OP_BINARY_OP, 0);  break;
-        //     case TK("-"):   emit(OP_BINARY_OP, 1);  break;
-        //     case TK("*"):   emit(OP_BINARY_OP, 2);  break;
-        //     case TK("/"):   emit(OP_BINARY_OP, 3);  break;
-        //     case TK("//"):  emit(OP_BINARY_OP, 4);  break;
-        //     case TK("%"):   emit(OP_BINARY_OP, 5);  break;
-        //     case TK("**"):  emit(OP_BINARY_OP, 6);  break;
-
-        //     case TK("<"):   emit(OP_COMPARE_OP, 0);    break;
-        //     case TK("<="):  emit(OP_COMPARE_OP, 1);    break;
-        //     case TK("=="):  emit(OP_COMPARE_OP, 2);    break;
-        //     case TK("!="):  emit(OP_COMPARE_OP, 3);    break;
-        //     case TK(">"):   emit(OP_COMPARE_OP, 4);    break;
-        //     case TK(">="):  emit(OP_COMPARE_OP, 5);    break;
-        //     case TK("in"):      emit(OP_CONTAINS_OP, 0);   break;
-        //     case TK("not in"):  emit(OP_CONTAINS_OP, 1);   break;
-        //     case TK("is"):      emit(OP_IS_OP, 0);         break;
-        //     case TK("is not"):  emit(OP_IS_OP, 1);         break;
-
-        //     case TK("<<"):  emit(OP_BITWISE_OP, 0);    break;
-        //     case TK(">>"):  emit(OP_BITWISE_OP, 1);    break;
-        //     case TK("&"):   emit(OP_BITWISE_OP, 2);    break;
-        //     case TK("|"):   emit(OP_BITWISE_OP, 3);    break;
-        //     case TK("^"):   emit(OP_BITWISE_OP, 4);    break;
-        //     default: UNREACHABLE();
-        // }
+        auto e = expr_prev_line<BinaryExpr>();
+        e->op = prev().type;
+        e->lhs = ctx()->s_expr.popx();
+        parse_expression(rules[e->op].precedence + 1);
+        e->rhs = ctx()->s_expr.popx();
+        ctx()->s_expr.push(std::move(e));
     }
 
     void exprNot() {
-        parse_expression((Precedence)(PREC_LOGICAL_NOT + 1));
+        parse_expression(PREC_LOGICAL_NOT + 1);
         ctx()->s_expr.push(
-            std::make_unique<NotExpr>(ctx()->s_expr.popx())
+            expr_prev_line<NotExpr>(ctx()->s_expr.popx())
         );
-        // emit(OP_UNARY_NOT);
     }
 
     void exprUnaryOp(){
         TokenIndex type = prev().type;
-        parse_expression((Precedence)(PREC_UNARY + 1));
-        ctx()->s_expr.push(
-            std::make_unique<UnaryExpr>(type, ctx()->s_expr.popx())
-        );
-        // switch (type) {
-        //     case TK("-"):     emit(OP_UNARY_NEGATIVE); break;
-        //     case TK("*"):     emit(OP_UNARY_STAR, co()->_rvalue);   break;
-        //     default: UNREACHABLE();
-        // }
+        parse_expression(PREC_UNARY + 1);
+        Expr_ e;
+        switch(type){
+            case TK("-"):
+                e = expr_prev_line<NegatedExpr>(ctx()->s_expr.popx());
+            case TK("*"):
+                e = expr_prev_line<StarredExpr>(ctx()->s_expr.popx());
+            default: UNREACHABLE();
+        }
+        ctx()->s_expr.push(std::move(e));
     }
 
-    // () is just for change precedence, so we don't need to push it into stack
+    // () is just for change precedence
     void exprGroup(){
         match_newlines(mode()==REPL_MODE);
         EXPR_TUPLE();
@@ -507,52 +380,37 @@ private:
     // }
 
     template<typename T>
-    void _consume_comp(){
-
+    void _consume_comp(Expr_ expr){
+        static_assert(std::is_base_of<CompExpr, T>::value);
+        std::unique_ptr<CompExpr> ce = std::make_unique<T>();
+        ce->expr = std::move(expr);
+        // ...
+        ctx()->s_expr.push(std::move(ce));
     }
 
     void exprList() {
-        int ARGC = 0;
+        auto e = expr_prev_line<ListExpr>();
         do {
             match_newlines(mode()==REPL_MODE);
             if (curr().type == TK("]")) break;
-            EXPR(); ARGC++;
+            EXPR();
+            e->items.push_back(ctx()->s_expr.popx());
             match_newlines(mode()==REPL_MODE);
-            if(ARGC == 1 && match(TK("for"))){
-                _consume_comp<ListCompExpr>();
+            if(e->items.size()==1 && match(TK("for"))){
+                _consume_comp<ListCompExpr>(std::move(e->items[0]));
                 consume(TK("]"));
                 return;
             }
         } while (match(TK(",")));
         match_newlines(mode()==REPL_MODE);
         consume(TK("]"));
-        auto list_expr = std::make_unique<ListExpr>();
-        list_expr->items.resize(ARGC);
-        for(int i=ARGC-1; i>=0; i--) list_expr->items[i] = ctx()->s_expr.popx();
-        ctx()->s_expr.push(std::move(list_expr));
-
-        // int _patch = emit(OP_NO_OP);
-        // int _body_start = co()->codes.size();
-        // int ARGC = 0;
-        // do {
-        //     match_newlines(mode()==REPL_MODE);
-        //     if (curr().type == TK("]")) break;
-        //     EXPR(); ARGC++;
-        //     match_newlines(mode()==REPL_MODE);
-        //     if(ARGC == 1 && match(TK("for"))){
-        //         _consume_comp(OP_BUILD_LIST, OP_LIST_APPEND, _patch, _body_start);
-        //         consume(TK("]"));
-        //         return;
-        //     }
-        // } while (match(TK(",")));
-        // match_newlines(mode()==REPL_MODE);
-        // consume(TK("]"));
-        // emit(OP_BUILD_LIST, ARGC);
+        ctx()->s_expr.push(std::move(e));
     }
 
+    // {...} may be dict or set
     void exprMap() {
         bool parsing_dict = false;
-        int ARGC = 0;
+        std::vector<Expr_> items;
         do {
             match_newlines(mode()==REPL_MODE);
             if (curr().type == TK("}")) break;
@@ -561,62 +419,33 @@ private:
             if(parsing_dict){
                 consume(TK(":"));
                 EXPR();
-                Expression_ value = ctx()->s_expr.popx();
-                ctx()->s_expr.push(
-                    std::make_unique<DictItemExpr>(ctx()->s_expr.popx(), std::move(value))
-                );
+                auto dict_item = expr_prev_line<DictItemExpr>();
+                dict_item->key = ctx()->s_expr.popx();
+                dict_item->value = ctx()->s_expr.popx();
+                items.push_back(std::move(dict_item));
+            }else{
+                items.push_back(ctx()->s_expr.popx());
             }
-            ARGC++;
             match_newlines(mode()==REPL_MODE);
-            if(ARGC == 1 && match(TK("for"))){
-                if(parsing_dict) _consume_comp<DictCompExpr>();
-                else _consume_comp<SetCompExpr>();
+            if(items.size()==1 && match(TK("for"))){
+                if(parsing_dict) _consume_comp<DictCompExpr>(std::move(items[0]));
+                else _consume_comp<SetCompExpr>(std::move(items[0]));
                 consume(TK("}"));
                 return;
             }
         } while (match(TK(",")));
         consume(TK("}"));
-        if(ARGC == 0 || parsing_dict){
-            auto e = std::make_unique<DictExpr>();
-            e->items.resize(ARGC);
-            for(int i=ARGC-1; i>=0; i--) e->items[i] = ctx()->s_expr.popx();
+        if(items.size()==0 || parsing_dict){
+            auto e = expr_prev_line<DictExpr>(std::move(items));
             ctx()->s_expr.push(std::move(e));
         }else{
-            auto e = std::make_unique<SetExpr>();
-            e->items.resize(ARGC);
-            for(int i=ARGC-1; i>=0; i--) e->items[i] = ctx()->s_expr.popx();
+            auto e = expr_prev_line<SetExpr>(std::move(items));
             ctx()->s_expr.push(std::move(e));
         }
-        // int _patch = emit(OP_NO_OP);
-        // int _body_start = co()->codes.size();
-        // bool parsing_dict = false;
-        // int ARGC = 0;
-        // do {
-        //     match_newlines(mode()==REPL_MODE);
-        //     if (curr().type == TK("}")) break;
-        //     EXPR();
-        //     if(curr().type == TK(":")) parsing_dict = true;
-        //     if(parsing_dict){
-        //         consume(TK(":"));
-        //         EXPR();
-        //     }
-        //     ARGC++;
-        //     match_newlines(mode()==REPL_MODE);
-        //     if(ARGC == 1 && match(TK("for"))){
-        //         if(parsing_dict) _consume_comp(OP_BUILD_MAP, OP_MAP_ADD, _patch, _body_start);
-        //         else _consume_comp(OP_BUILD_SET, OP_SET_ADD, _patch, _body_start);
-        //         consume(TK("}"));
-        //         return;
-        //     }
-        // } while (match(TK(",")));
-        // consume(TK("}"));
-
-        // if(ARGC == 0 || parsing_dict) emit(OP_BUILD_MAP, ARGC);
-        // else emit(OP_BUILD_SET, ARGC);
     }
 
     void exprCall() {
-        auto e = std::make_unique<CallExpr>();
+        auto e = _expr<CallExpr>();
         do {
             match_newlines(mode()==REPL_MODE);
             if (curr().type==TK(")")) break;
@@ -648,69 +477,49 @@ private:
 
     void exprName(){
         ctx()->s_expr.push(
-            std::make_unique<NameExpr>(prev().str(), name_scope())
+            expr_prev_line<NameExpr>(prev().str(), name_scope())
         );
     }
 
     void exprAttrib() {
         consume(TK("@id"));
         ctx()->s_expr.push(
-            std::make_unique<AttribExpr>(ctx()->s_expr.popx(), prev().str())
+            expr_prev_line<AttribExpr>(ctx()->s_expr.popx(), prev().str())
         );
     }
 
-    // [:], [:b]
-    // [a], [a:], [a:b]
     void exprSubscr() {
-        Expression_ a = nullptr;
-        Expression_ b = nullptr;
-        if(match(TK(":"))){
-            if(match(TK("]"))){         // [:]
-                
-            }else{                      // [:b]
-                EXPR_TUPLE();
-                consume(TK("]"));
-            }
-            emit(OP_BUILD_SLICE);
-        }else{
+        auto e = expr_prev_line<SubscrExpr>();
+        std::vector<Expr_> items;
+        do {
             EXPR_TUPLE();
-            if(match(TK(":"))){
-                if(match(TK("]"))){     // [a:]
-                    emit(OP_LOAD_NONE);
-                }else{                  // [a:b]
-                    EXPR_TUPLE();
-                    consume(TK("]"));
+            items.push_back(ctx()->s_expr.popx());
+        } while(match(TK(":")));
+        consume(TK("]"));
+        switch(items.size()){
+            case 1:
+                e->b = std::move(items[0]);
+                break;
+            case 2: case 3: {
+                auto slice = expr_prev_line<SliceExpr>();
+                slice->start = std::move(items[0]);
+                slice->stop = std::move(items[1]);
+                if(items.size()==3){
+                    slice->step = std::move(items[2]);
                 }
-                emit(OP_BUILD_SLICE);
-            }else{                      // [a]
-                consume(TK("]"));
-            }
+                e->b = std::move(slice);
+            } break;
+            default: SyntaxError(); break;
         }
-
-        // emit(OP_BUILD_INDEX, (int)(co()->_rvalue>0));
+        ctx()->s_expr.push(std::move(e));
     }
 
-    void exprValue() {
+    void exprLiteral0() {
         ctx()->s_expr.push(
-            std::make_unique<SpecialLiteralExpr>(prev().type)
+            expr_prev_line<Literal0Expr>(prev().type)
         );
     }
 
-    int emit(Opcode opcode, int arg=-1, bool keepline=false) {
-        int line = prev().line;
-        co()->codes.push_back(
-            Bytecode{(uint8_t)opcode, (uint16_t)ctx()->curr_block_i, arg, line}
-        );
-        int i = co()->codes.size() - 1;
-        if(keepline && i>=1) co()->codes[i].line = co()->codes[i-1].line;
-        return i;
-    }
-
-    inline void patch_jump(int addr_index) {
-        int target = co()->codes.size();
-        co()->codes[addr_index].arg = target;
-    }
-
     void compile_block_body() {
         consume(TK(":"));
         if(curr().type!=TK("@eol") && curr().type!=TK("@eof")){
@@ -778,10 +587,11 @@ private:
         consume_end_stmt();
     }
 
-    // a = 1 + 2
-    // ['a', '1', '2', '+', '=']
-    // 
-    void parse_expression(Precedence precedence, bool allowslice=false) {
+    void parse_expression(int precedence){
+        parse_expression((Precedence)precedence);
+    }
+
+    void parse_expression(Precedence precedence) {
         advance();
         PrattCallback prefix = rules[prev().type].prefix;
         if (prefix == nullptr) SyntaxError(Str("expected an expression, but got ") + TK_STR(prev().type));
diff --git a/src/expr.h b/src/expr.h
index 0ae035bf..4740b9f1 100644
--- a/src/expr.h
+++ b/src/expr.h
@@ -8,115 +8,262 @@
 
 namespace pkpy{
 
-struct Expression{
-    virtual Str to_string() const = 0;
+struct CodeEmitContext;
+struct Expr{
+    int line = 0;
+    virtual Str str() const = 0;
+    ~Expr() = default;
+    virtual void emit(CodeEmitContext* ctx) = 0;
 };
 
-struct NameExpr: Expression{
+struct CodeEmitContext{
+    CodeObject_ co;
+    VM* vm;
+    stack<Expr_> s_expr;
+
+    CodeEmitContext(VM* vm, CodeObject_ co): co(co) {}
+    CodeEmitContext(const CodeEmitContext&) = delete;
+    CodeEmitContext& operator=(const CodeEmitContext&) = delete;
+    CodeEmitContext(CodeEmitContext&&) = delete;
+    CodeEmitContext& operator=(CodeEmitContext&&) = delete;
+
+    int curr_block_i = 0;
+    bool is_compiling_class = false;
+
+    bool is_curr_block_loop() const {
+        return co->blocks[curr_block_i].type == FOR_LOOP || co->blocks[curr_block_i].type == WHILE_LOOP;
+    }
+
+    void enter_block(CodeBlockType type){
+        co->blocks.push_back(CodeBlock{
+            type, curr_block_i, (int)co->codes.size()
+        });
+        curr_block_i = co->blocks.size()-1;
+    }
+
+    void exit_block(){
+        co->blocks[curr_block_i].end = co->codes.size();
+        curr_block_i = co->blocks[curr_block_i].parent;
+        if(curr_block_i < 0) UNREACHABLE();
+    }
+
+    // clear the expression stack and generate bytecode
+    void emit_expr(){
+        if(s_expr.size() != 1) UNREACHABLE();
+        Expr_ expr = s_expr.popx();
+        // emit
+        // ...
+    }
+
+    int emit(Opcode opcode, int arg, int line) {
+        co->codes.push_back(
+            Bytecode{(uint8_t)opcode, (uint16_t)curr_block_i, arg, line}
+        );
+        int i = co->codes.size() - 1;
+        if(line==BC_KEEPLINE && i>=1) co->codes[i].line = co->codes[i-1].line;
+        return i;
+    }
+
+    void patch_jump(int index) {
+        int target = co->codes.size();
+        co->codes[index].arg = target;
+    }
+
+    bool add_label(StrName label){
+        if(co->labels.count(label)) return false;
+        co->labels[label] = co->codes.size();
+        return true;
+    }
+
+    int add_name(StrName name, NameScope scope){
+        if(scope == NAME_LOCAL && co->global_names.count(name)) scope = NAME_GLOBAL;
+        auto p = std::make_pair(name, scope);
+        for(int i=0; i<co->names.size(); i++){
+            if(co->names[i] == p) return i;
+        }
+        co->names.push_back(p);
+        return co->names.size() - 1;
+    }
+
+    int add_const(PyObject* v){
+        co->consts.push_back(v);
+        return co->consts.size() - 1;
+    }
+};
+
+struct NameExpr: Expr{
     Str name;
     NameScope scope;
     NameExpr(const Str& name, NameScope scope): name(name), scope(scope) {}
     NameExpr(Str&& name, NameScope scope): name(std::move(name)), scope(scope) {}
-    Str to_string() const override { return name; }
+
+    Str str() const override { return "$" + name; }
+
+    void emit(CodeEmitContext* ctx) override {
+        int index = ctx->add_name(name, scope);
+        ctx->emit(OP_LOAD_NAME, index, line);
+    }
 };
 
-struct UnaryExpr: Expression{
-    TokenIndex op;
-    Expression_ child;
-    UnaryExpr(TokenIndex op, Expression_&& child): op(op), child(std::move(child)) {}
-    Str to_string() const override { return TK_STR(op); }
+struct StarredExpr: Expr{
+    Expr_ child;
+    StarredExpr(Expr_&& child): child(std::move(child)) {}
+    Str str() const override { return "*"; }
+
+    void emit(CodeEmitContext* ctx) override {
+        child->emit(ctx);
+        ctx->emit(OP_UNARY_STAR, (int)false, line);
+    }
 };
 
-struct NotExpr: Expression{
-    Expression_ child;
-    NotExpr(Expression_&& child): child(std::move(child)) {}
-    Str to_string() const override { return "not"; }
+struct NegatedExpr: Expr{
+    Expr_ child;
+    NegatedExpr(Expr_&& child): child(std::move(child)) {}
+    Str str() const override { return "-"; }
+
+    void emit(CodeEmitContext* ctx) override {
+        child->emit(ctx);
+        ctx->emit(OP_UNARY_NEGATIVE, BC_NOARG, line);
+    }
 };
 
-struct AndExpr: Expression{
-    Expression_ lhs;
-    Expression_ rhs;
-    AndExpr(Expression_&& lhs, Expression_&& rhs): lhs(std::move(lhs)), rhs(std::move(rhs)) {}
-    Str to_string() const override { return "and"; }
+struct NotExpr: Expr{
+    Expr_ child;
+    NotExpr(Expr_&& child): child(std::move(child)) {}
+    Str str() const override { return "not"; }
+
+    void emit(CodeEmitContext* ctx) override {
+        child->emit(ctx);
+        ctx->emit(OP_UNARY_NOT, BC_NOARG, line);
+    }
 };
 
-struct OrExpr: Expression{
-    Expression_ lhs;
-    Expression_ rhs;
-    OrExpr(Expression_&& lhs, Expression_&& rhs): lhs(std::move(lhs)), rhs(std::move(rhs)) {}
-    Str to_string() const override { return "or"; }
+struct AndExpr: Expr{
+    Expr_ lhs;
+    Expr_ rhs;
+    Str str() const override { return "and"; }
+
+    void emit(CodeEmitContext* ctx) override {
+        lhs->emit(ctx);
+        int patch = ctx->emit(OP_JUMP_IF_FALSE_OR_POP, BC_NOARG, line);
+        rhs->emit(ctx);
+        ctx->patch_jump(patch);
+    }
+};
+
+struct OrExpr: Expr{
+    Expr_ lhs;
+    Expr_ rhs;
+    Str str() const override { return "or"; }
+
+    void emit(CodeEmitContext* ctx) override {
+        lhs->emit(ctx);
+        int patch = ctx->emit(OP_JUMP_IF_TRUE_OR_POP, BC_NOARG, line);
+        rhs->emit(ctx);
+        ctx->patch_jump(patch);
+    }
 };
 
 // [None, True, False, ...]
-struct SpecialLiteralExpr: Expression{
+struct Literal0Expr: Expr{
     TokenIndex token;
-    SpecialLiteralExpr(TokenIndex token): token(token) {}
-    Str to_string() const override { return TK_STR(token); }
+    Literal0Expr(TokenIndex token): token(token) {}
+    Str str() const override { return TK_STR(token); }
 
-    void gen(){
-        // switch (token) {
-        //     case TK("None"):    emit(OP_LOAD_NONE);  break;
-        //     case TK("True"):    emit(OP_LOAD_TRUE);  break;
-        //     case TK("False"):   emit(OP_LOAD_FALSE); break;
-        //     case TK("..."):     emit(OP_LOAD_ELLIPSIS); break;
-        //     default: UNREACHABLE();
-        // }
+    void emit(CodeEmitContext* ctx) override {
+        switch (token) {
+            case TK("None"):    ctx->emit(OP_LOAD_NONE, BC_NOARG, line); break;
+            case TK("True"):    ctx->emit(OP_LOAD_TRUE, BC_NOARG, line); break;
+            case TK("False"):   ctx->emit(OP_LOAD_FALSE, BC_NOARG, line); break;
+            case TK("..."):     ctx->emit(OP_LOAD_ELLIPSIS, BC_NOARG, line); break;
+            default: UNREACHABLE();
+        }
     }
 };
 
 // @num, @str which needs to invoke OP_LOAD_CONST
-struct LiteralExpr: Expression{
+struct LiteralExpr: Expr{
     TokenValue value;
     LiteralExpr(TokenValue value): value(value) {}
-    Str to_string() const override { return "literal"; }
+    Str str() const override {
+        if(std::holds_alternative<i64>(value)){
+            return std::to_string(std::get<i64>(value));
+        }
+
+        if(std::holds_alternative<f64>(value)){
+            return std::to_string(std::get<f64>(value));
+        }
+
+        if(std::holds_alternative<Str>(value)){
+            return std::get<Str>(value).escape(true);
+        }
+
+        UNREACHABLE();
+    }
+
+    void emit(CodeEmitContext* ctx) override {
+        VM* vm = ctx->vm;
+        PyObject* obj = nullptr;
+        if(std::holds_alternative<i64>(value)){
+            obj = VAR(std::get<i64>(value));
+        }
+
+        if(std::holds_alternative<f64>(value)){
+            obj = VAR(std::get<f64>(value));
+        }
+
+        if(std::holds_alternative<Str>(value)){
+            obj = VAR(std::get<Str>(value));
+        }
+
+        if(!obj) UNREACHABLE();
+        int index = ctx->add_const(obj);
+        ctx->emit(OP_LOAD_CONST, index, line);
+    }
 };
 
-struct SliceExpr: Expression{
-    Expression_ start;
-    Expression_ stop;
-    Expression_ step;
-    SliceExpr(Expression_&& start, Expression_&& stop, Expression_&& step):
-        start(std::move(start)), stop(std::move(stop)), step(std::move(step)) {}
-    Str to_string() const override { return "slice"; }
+struct SliceExpr: Expr{
+    Expr_ start;
+    Expr_ stop;
+    Expr_ step;
+    Str str() const override { return "slice()"; }
 };
 
-struct ListExpr: Expression{
-    std::vector<Expression_> items;
-    Str to_string() const override { return "[]"; }
+struct ListExpr: Expr{
+    std::vector<Expr_> items;
+    Str str() const override { return "[]"; }
 };
 
-struct DictExpr: Expression{
-    std::vector<Expression_> items;     // each item is a DictItemExpr
-    Str to_string() const override { return "{}"; }
+struct DictExpr: Expr{
+    std::vector<Expr_> items;     // each item is a DictItemExpr
+    DictExpr(std::vector<Expr_>&& items): items(std::move(items)) {}
+    Str str() const override { return "{}"; }
 };
 
-struct SetExpr: Expression{
-    std::vector<Expression_> items;
-    Str to_string() const override { return "{}"; }
+struct SetExpr: Expr{
+    std::vector<Expr_> items;
+    Set(std::vector<Expr_>&& items): items(std::move(items)) {}
+    Str str() const override { return "{}"; }
 };
 
-
-struct TupleExpr: Expression{
-    std::vector<Expression_> items;
-    TupleExpr(std::vector<Expression_>&& items): items(std::move(items)) {}
-    Str to_string() const override { return "(a, b, c)"; }
+struct TupleExpr: Expr{
+    std::vector<Expr_> items;
+    Str str() const override { return "tuple()"; }
 };
 
-struct CompExpr: Expression{
-    Expression_ expr;       // loop expr
-    Expression_ vars;       // loop vars
-    Expression_ iter;       // loop iter
-    Expression_ cond;       // optional if condition
+struct CompExpr: Expr{
+    Expr_ expr;       // loop expr
+    Expr_ vars;       // loop vars
+    Expr_ iter;       // loop iter
+    Expr_ cond;       // optional if condition
     virtual void emit_expr() = 0;
 };
 
 // a:b
-struct DictItemExpr: Expression{
-    Expression_ key;
-    Expression_ value;
-    DictItemExpr(Expression_&& key, Expression_&& value)
-        : key(std::move(key)), value(std::move(value)) {}
-    Str to_string() const override { return "dict item"; }
+struct DictItemExpr: Expr{
+    Expr_ key;
+    Expr_ value;
+    Str str() const override { return "k:v"; }
 };
 
 struct ListCompExpr: CompExpr{
@@ -128,73 +275,144 @@ struct DictCompExpr: CompExpr{
 struct SetCompExpr: CompExpr{
 };
 
-struct LambdaExpr: Expression{
+struct LambdaExpr: Expr{
     Function func;
     NameScope scope;
-    LambdaExpr(Function&& func, NameScope scope): func(std::move(func)), scope(scope) {}
-    Str to_string() const override { return "lambda"; }
+    Str str() const override { return "<lambda>"; }
+
+    void emit(CodeEmitContext* ctx) override {
+        VM* vm = ctx->vm;
+        ctx->emit(OP_LOAD_FUNCTION, ctx->add_const(VAR(func)), line);
+        if(scope == NAME_LOCAL) ctx->emit(OP_SETUP_CLOSURE, BC_NOARG, line);
+    }
 };
 
-struct FStringExpr: Expression{
+struct FStringExpr: Expr{
     Str src;
     FStringExpr(const Str& src): src(src) {}
-    Str to_string() const override { return "@fstr"; }
+    Str str() const override {
+        return "f" + src.escape(true);
+    }
+
+    void emit(CodeEmitContext* ctx) override {
+        VM* vm = ctx->vm;
+        static const std::regex pattern(R"(\{(.*?)\})");
+        std::sregex_iterator begin(src.begin(), src.end(), pattern);
+        std::sregex_iterator end;
+        int size = 0;
+        int i = 0;
+        for(auto it = begin; it != end; it++) {
+            std::smatch m = *it;
+            if (i < m.position()) {
+                std::string literal = src.substr(i, m.position() - i);
+                ctx->emit(OP_LOAD_CONST, ctx->add_const(VAR(literal)), line);
+                size++;
+            }
+            ctx->emit(OP_LOAD_EVAL_FN, BC_NOARG, line);
+            ctx->emit(OP_LOAD_CONST, ctx->add_const(VAR(m[1].str())), line);
+            ctx->emit(OP_CALL, 1, line);
+            size++;
+            i = (int)(m.position() + m.length());
+        }
+        if (i < src.size()) {
+            std::string literal = src.substr(i, src.size() - i);
+            ctx->emit(OP_LOAD_CONST, ctx->add_const(VAR(literal)), line);
+            size++;
+        }
+        ctx->emit(OP_BUILD_STRING, size, line);
+    }
 };
 
-struct SubscrExpr: Expression{
-    Expression_ a;
-    Expression_ b;
-    SubscrExpr(Expression_&& a, Expression_&& b): a(std::move(a)), b(std::move(b)) {}
-    Str to_string() const override { return "a[b]"; }
+struct SubscrExpr: Expr{
+    Expr_ a;
+    Expr_ b;
+    Str str() const override { return "a[b]"; }
 };
 
-struct AttribExpr: Expression{
-    Expression_ a;
+struct AttribExpr: Expr{
+    Expr_ a;
     Str b;
-    AttribExpr(Expression_ a, const Str& b): a(std::move(a)), b(b) {}
-    AttribExpr(Expression_ a, Str&& b): a(std::move(a)), b(std::move(b)) {}
-    Str to_string() const override { return "."; }
+    AttribExpr(Expr_ a, const Str& b): a(std::move(a)), b(b) {}
+    AttribExpr(Expr_ a, Str&& b): a(std::move(a)), b(std::move(b)) {}
+    Str str() const override { return "a.b"; }
 };
 
-struct AssignExpr: Expression{
-    Expression_ lhs;
-    Expression_ rhs;
-    AssignExpr(Expression_&& lhs, Expression_&& rhs): lhs(std::move(lhs)), rhs(std::move(rhs)) {}
-    Str to_string() const override { return "="; }
+struct AssignExpr: Expr{
+    Expr_ lhs;
+    Expr_ rhs;
+    Str str() const override { return "="; }
 };
 
-struct InplaceAssignExpr: Expression{
+struct InplaceAssignExpr: Expr{
     TokenIndex op;
-    Expression_ lhs;
-    Expression_ rhs;
-    InplaceAssignExpr(TokenIndex op, Expression_&& lhs, Expression_&& rhs)
-        : op(op), lhs(std::move(lhs)), rhs(std::move(rhs)) {}
-    Str to_string() const override { return TK_STR(op); }
+    Expr_ lhs;
+    Expr_ rhs;
+    Str str() const override { return TK_STR(op); }
 };
 
-
-struct CallExpr: Expression{
-    std::vector<Expression_> args;
-    std::vector<std::pair<Str, Expression_>> kwargs;
-    Str to_string() const override { return "()"; }
+struct CallExpr: Expr{
+    std::vector<Expr_> args;
+    std::vector<std::pair<Str, Expr_>> kwargs;
+    Str str() const override { return "()"; }
 };
 
-struct BinaryExpr: Expression{
+struct BinaryExpr: Expr{
     TokenIndex op;
-    Expression_ lhs;
-    Expression_ rhs;
-    BinaryExpr(TokenIndex op, Expression_&& lhs, Expression_&& rhs)
-        : op(op), lhs(std::move(lhs)), rhs(std::move(rhs)) {}
-    Str to_string() const override { return TK_STR(op); }
+    Expr_ lhs;
+    Expr_ rhs;
+    Str str() const override { return TK_STR(op); }
+
+    void emit(CodeEmitContext* ctx) override {
+        lhs->emit(ctx);
+        rhs->emit(ctx);
+        switch (op) {
+            case TK("+"):   ctx->emit(OP_BINARY_OP, 0, line);  break;
+            case TK("-"):   ctx->emit(OP_BINARY_OP, 1, line);  break;
+            case TK("*"):   ctx->emit(OP_BINARY_OP, 2, line);  break;
+            case TK("/"):   ctx->emit(OP_BINARY_OP, 3, line);  break;
+            case TK("//"):  ctx->emit(OP_BINARY_OP, 4, line);  break;
+            case TK("%"):   ctx->emit(OP_BINARY_OP, 5, line);  break;
+            case TK("**"):  ctx->emit(OP_BINARY_OP, 6, line);  break;
+
+            case TK("<"):   ctx->emit(OP_COMPARE_OP, 0, line);    break;
+            case TK("<="):  ctx->emit(OP_COMPARE_OP, 1, line);    break;
+            case TK("=="):  ctx->emit(OP_COMPARE_OP, 2, line);    break;
+            case TK("!="):  ctx->emit(OP_COMPARE_OP, 3, line);    break;
+            case TK(">"):   ctx->emit(OP_COMPARE_OP, 4, line);    break;
+            case TK(">="):  ctx->emit(OP_COMPARE_OP, 5, line);    break;
+            case TK("in"):      ctx->emit(OP_CONTAINS_OP, 0, line);   break;
+            case TK("not in"):  ctx->emit(OP_CONTAINS_OP, 1, line);   break;
+            case TK("is"):      ctx->emit(OP_IS_OP, 0, line);         break;
+            case TK("is not"):  ctx->emit(OP_IS_OP, 1, line);         break;
+
+            case TK("<<"):  ctx->emit(OP_BITWISE_OP, 0, line);    break;
+            case TK(">>"):  ctx->emit(OP_BITWISE_OP, 1, line);    break;
+            case TK("&"):   ctx->emit(OP_BITWISE_OP, 2, line);    break;
+            case TK("|"):   ctx->emit(OP_BITWISE_OP, 3, line);    break;
+            case TK("^"):   ctx->emit(OP_BITWISE_OP, 4, line);    break;
+            default: UNREACHABLE();
+        }
+    }
 };
 
-struct TernaryExpr: Expression{
-    Expression_ cond;
-    Expression_ true_expr;
-    Expression_ false_expr;
-    TernaryExpr(Expression_&& cond, Expression_&& true_expr, Expression_&& false_expr)
-        : cond(std::move(cond)), true_expr(std::move(true_expr)), false_expr(std::move(false_expr)) {}
-    Str to_string() const override { return "?"; }
+struct TernaryExpr: Expr{
+    Expr_ cond;
+    Expr_ true_expr;
+    Expr_ false_expr;
+
+    Str str() const override {
+        return "cond ? true_expr : false_expr";
+    }
+
+    void emit(CodeEmitContext* ctx) override {
+        cond->emit(ctx);
+        int patch = ctx->emit(OP_POP_JUMP_IF_FALSE, BC_NOARG, cond->line);
+        true_expr->emit(ctx);
+        int patch_2 = ctx->emit(OP_JUMP_ABSOLUTE, BC_NOARG, true_expr->line);
+        ctx->patch_jump(patch);
+        false_expr->emit(ctx);
+        ctx->patch_jump(patch_2);
+    }
 };
 
 
diff --git a/src/lexer.h b/src/lexer.h
index 8412aa4c..8b997ca5 100644
--- a/src/lexer.h
+++ b/src/lexer.h
@@ -72,8 +72,7 @@ struct Token{
 enum Precedence {
   PREC_NONE,
   PREC_ASSIGNMENT,    // =
-  PREC_COMMA,         // ,
-  PREC_SLICE,         // :   (only available inside a subscript expression)
+  PREC_TUPLE,         // ,
   PREC_TERNARY,       // ?:
   PREC_LOGICAL_OR,    // or
   PREC_LOGICAL_AND,   // and