diff --git a/x/io/_demo/asyncdemo/async.go b/x/io/_demo/asyncdemo/async.go
index 02b4475a..519f74fb 100644
--- a/x/io/_demo/asyncdemo/async.go
+++ b/x/io/_demo/asyncdemo/async.go
@@ -4,6 +4,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"strings"
 	"time"
 
 	"github.com/goplus/llgo/x/io"
@@ -28,12 +29,13 @@ func (r *Response) Text() (resolve io.Promise[string]) {
 
 func (r *Response) TextCompiled() *io.PromiseImpl[string] {
 	P := &io.PromiseImpl[string]{}
+	P.Debug = "Text"
 	P.Func = func(resolve func(string, error)) {
 		for {
 			switch P.Prev = P.Next; P.Prev {
 			case 0:
-				resolve(r.mockBody, nil)
 				P.Next = -1
+				resolve(r.mockBody, nil)
 				return
 			default:
 				panic("Promise already done")
@@ -43,24 +45,58 @@ func (r *Response) TextCompiled() *io.PromiseImpl[string] {
 	return P
 }
 
-func HttpGet(url string, callback func(resp *Response, err error)) {
-	resp := &Response{StatusCode: 200}
-	callback(resp, nil)
+func Http(method string, url string, callback func(resp *Response, err error)) {
+	go func() {
+		body := ""
+		if strings.HasPrefix(url, "http://example.com/user/") {
+			name := url[len("http://example.com/user/"):]
+			body = `{"name":"` + name + `"}`
+		} else if strings.HasPrefix(url, "http://example.com/score/") {
+			body = "99.5"
+		}
+		time.Sleep(200 * time.Millisecond)
+		resp := &Response{StatusCode: 200, mockBody: body}
+		callback(resp, nil)
+	}()
 }
 
 func AsyncHttpGet(url string) (resolve io.Promise[*Response]) {
-	HttpGet(url, resolve)
+	Http("GET", url, resolve)
 	return
 }
 
 func AsyncHttpGetCompiled(url string) *io.PromiseImpl[*Response] {
 	P := &io.PromiseImpl[*Response]{}
+	P.Debug = "HttpGet"
 	P.Func = func(resolve func(*Response, error)) {
 		for {
 			switch P.Prev = P.Next; P.Prev {
 			case 0:
-				HttpGet(url, resolve)
 				P.Next = -1
+				Http("GET", url, resolve)
+				return
+			default:
+				panic("Promise already done")
+			}
+		}
+	}
+	return P
+}
+
+func AsyncHttpPost(url string) (resolve io.Promise[*Response]) {
+	Http("POST", url, resolve)
+	return
+}
+
+func AsyncHttpPostCompiled(url string) *io.PromiseImpl[*Response] {
+	P := &io.PromiseImpl[*Response]{}
+	P.Debug = "HttpPost"
+	P.Func = func(resolve func(*Response, error)) {
+		for {
+			switch P.Prev = P.Next; P.Prev {
+			case 0:
+				P.Next = -1
+				Http("POST", url, resolve)
 				return
 			default:
 				panic("Promise already done")
@@ -76,8 +112,8 @@ type User struct {
 	Name string
 }
 
-func GetUser(uid string) (resolve io.Promise[User]) {
-	resp, err := AsyncHttpGet("http://example.com/user/" + uid).Await()
+func GetUser(name string) (resolve io.Promise[User]) {
+	resp, err := AsyncHttpGet("http://example.com/user/" + name).Await()
 	if err != nil {
 		resolve(User{}, err)
 		return
@@ -88,8 +124,6 @@ func GetUser(uid string) (resolve io.Promise[User]) {
 		return
 	}
 
-	resp.mock(`{"name":"Alice"}`)
-
 	body, err := resp.Text().Await()
 	if err != nil {
 		resolve(User{}, err)
@@ -105,21 +139,29 @@ func GetUser(uid string) (resolve io.Promise[User]) {
 	return
 }
 
-func GetUserCompiled(uid string) *io.PromiseImpl[User] {
+func GetUserCompiled(name string) *io.PromiseImpl[User] {
 	var state1 *io.PromiseImpl[*Response]
 	var state2 *io.PromiseImpl[string]
 
 	P := &io.PromiseImpl[User]{}
+	P.Debug = "GetUser"
 	P.Func = func(resolve func(User, error)) {
 		for {
 			switch P.Prev = P.Next; P.Prev {
 			case 0:
-				state1 = AsyncHttpGetCompiled("http://example.com/user/" + uid)
 				P.Next = 1
+				state1 = AsyncHttpGetCompiled("http://example.com/user/" + name)
+				state1.Exec = P.Exec
+				state1.Call()
 				return
 			case 1:
-				state1.EnsureDone()
+				if !state1.Done() {
+					state1.Call()
+					return
+				}
+				P.Next = 2
 				resp, err := state1.Value, state1.Err
+				log.Printf("resp: %v, err: %v\n", resp, err)
 				if err != nil {
 					resolve(User{}, err)
 					return
@@ -130,26 +172,121 @@ func GetUserCompiled(uid string) *io.PromiseImpl[User] {
 					return
 				}
 
-				resp.mock(`{"name":"Alice"}`)
-
 				state2 = resp.TextCompiled()
-				P.Next = 2
+				state2.Exec = P.Exec
+				state2.Call()
+				log.Printf("TextCompiled state2: %v\n", state2)
 				return
 			case 2:
-				state2.EnsureDone()
+				if !state2.Done() {
+					state2.Call()
+					return
+				}
+				P.Next = -1
 				body, err := state2.Value, state2.Err
 				if err != nil {
 					resolve(User{}, err)
 					return
 				}
 				user := User{}
+				log.Printf("body: %v\n", body)
 				if err := json.Unmarshal([]byte(body), &user); err != nil {
 					resolve(User{}, err)
 					return
 				}
 
 				resolve(user, nil)
+				return
+			default:
+				panic(fmt.Sprintf("Promise already done, %+v", P))
+			}
+		}
+	}
+	return P
+}
+
+func GetScore() (resolve io.Promise[float64]) {
+	resp, err := AsyncHttpGet("http://example.com/score/").Await()
+	if err != nil {
+		resolve(0, err)
+		return
+	}
+
+	if resp.StatusCode != 200 {
+		resolve(0, fmt.Errorf("http status code: %d", resp.StatusCode))
+		return
+	}
+
+	body, err := resp.Text().Await()
+	if err != nil {
+		resolve(0, err)
+		return
+	}
+
+	score := 0.0
+	if _, err := fmt.Sscanf(body, "%f", &score); err != nil {
+		resolve(0, err)
+		return
+	}
+	resolve(score, nil)
+	return
+}
+
+func GetScoreCompiled() *io.PromiseImpl[float64] {
+	var state1 *io.PromiseImpl[*Response]
+	var state2 *io.PromiseImpl[string]
+
+	P := &io.PromiseImpl[float64]{}
+	P.Debug = "GetScore"
+	P.Func = func(resolve func(float64, error)) {
+		for {
+			switch P.Prev = P.Next; P.Prev {
+			case 0:
+				P.Next = 1
+				state1 = AsyncHttpGetCompiled("http://example.com/score/")
+				state1.Exec = P.Exec
+				state1.Call()
+				return
+			case 1:
+				if !state1.Done() {
+					state1.Call()
+					return
+				}
+				P.Next = 2
+				resp, err := state1.Value, state1.Err
+				if err != nil {
+					resolve(0, err)
+					return
+				}
+
+				if resp.StatusCode != 200 {
+					resolve(0, fmt.Errorf("http status code: %d", resp.StatusCode))
+					return
+				}
+
+				state2 = resp.TextCompiled()
+				state2.Exec = P.Exec
+				state2.Call()
+
+				return
+			case 2:
+				if !state2.Done() {
+					state2.Call()
+					return
+				}
 				P.Next = -1
+				body, err := state2.Value, state2.Err
+				if err != nil {
+					resolve(0, err)
+					return
+				}
+
+				score := 0.0
+				if _, err := fmt.Sscanf(body, "%f", &score); err != nil {
+					resolve(0, err)
+					return
+				}
+				resolve(score, nil)
 				return
 			default:
 				panic("Promise already done")
@@ -159,36 +296,55 @@ func GetUserCompiled(uid string) *io.PromiseImpl[User] {
 	return P
 }
 
-func GetScore() *io.Promise[float64] {
-	panic("todo: GetScore")
-}
-
-func GetScoreCompiled() *io.PromiseImpl[float64] {
-	P := &io.PromiseImpl[float64]{}
-	P.Func = func(resolve func(float64, error)) {
-		for {
-			switch P.Prev = P.Next; P.Prev {
-			case 0:
-				panic("todo: GetScore")
-			default:
-				panic("Promise already done")
-			}
-		}
+func DoUpdate(op string) (resolve io.Promise[io.Void]) {
+	resp, err := AsyncHttpPost("http://example.com/update/" + op).Await()
+	if err != nil {
+		resolve(io.Void{}, err)
+		return
 	}
-	return P
-}
 
-func DoUpdate(op string) *io.Promise[io.Void] {
-	panic("todo: DoUpdate")
+	if resp.StatusCode != 200 {
+		resolve(io.Void{}, fmt.Errorf("http status code: %d", resp.StatusCode))
+		return
+	}
+
+	resolve(io.Void{}, nil)
+	return
 }
 
 func DoUpdateCompiled(op string) *io.PromiseImpl[io.Void] {
+	var state1 *io.PromiseImpl[*Response]
+
 	P := &io.PromiseImpl[io.Void]{}
+	P.Debug = "DoUpdate"
 	P.Func = func(resolve func(io.Void, error)) {
 		for {
 			switch P.Prev = P.Next; P.Prev {
 			case 0:
-				panic("todo: DoUpdate")
+				P.Next = 1
+				state1 = AsyncHttpPostCompiled("http://example.com/update/" + op)
+				state1.Exec = P.Exec
+				state1.Call()
+				return
+			case 1:
+				if !state1.Done() {
+					state1.Call()
+					return
+				}
+				P.Next = -1
+				resp, err := state1.Value, state1.Err
+				if err != nil {
+					resolve(io.Void{}, err)
+					return
+				}
+
+				if resp.StatusCode != 200 {
+					resolve(io.Void{}, fmt.Errorf("http status code: %d", resp.StatusCode))
+					return
+				}
+
+				resolve(io.Void{}, nil)
+				return
 			default:
 				panic("Promise already done")
 			}
@@ -198,82 +354,103 @@ func DoUpdateCompiled(op string) *io.PromiseImpl[io.Void] {
 }
 
 func Demo() (resolve io.Promise[io.Void]) {
-	user, err := GetUser("123").Await()
+	user, err := GetUser("1").Await()
 	log.Println(user, err)
 
-	user, err = io.Race[User](GetUser("123"), GetUser("456"), GetUser("789")).Await()
+	user, err = io.Race[User](GetUser("2"), GetUser("3"), GetUser("4")).Await()
 	log.Println(user, err)
 
-	users, err := io.All[User]([]io.AsyncCall[User]{GetUser("123"), GetUser("456"), GetUser("789")}).Await()
+	users, err := io.All[User]([]io.AsyncCall[User]{GetUser("5"), GetUser("6"), GetUser("7")}).Await()
 	log.Println(users, err)
 
-	user, score, _, err := io.Await3[User, float64, io.Void](GetUser("123"), GetScore(), DoUpdate("update sth."))
+	user, score, _, err := io.Await3[User, float64, io.Void](GetUser("8"), GetScore(), DoUpdate("update sth."))
 	log.Println(user, score, err)
 
 	// TODO(lijie): select from multiple promises without channel
-	select {
-	case user := <-GetUser("123").Chan():
-		log.Println("user:", user)
-	case score := <-GetScore().Chan():
-		log.Println("score:", score)
-	case <-io.Timeout(5 * time.Second).Chan():
-		log.Println("timeout")
-	}
+	// select {
+	// case user := <-GetUser("123").Chan():
+	// 	log.Println("user:", user)
+	// case score := <-GetScore().Chan():
+	// 	log.Println("score:", score)
+	// case <-io.Timeout(5 * time.Second).Chan():
+	// 	log.Println("timeout")
+	// }
 	return
 }
 
 func DemoCompiled() *io.PromiseImpl[io.Void] {
 	var state1 *io.PromiseImpl[User]
 	var state2 *io.PromiseImpl[User]
-	var state3 *io.PromiseImpl[[]User]
+	var state3 *io.PromiseImpl[[]io.Result[User]]
 	var state4 *io.PromiseImpl[io.Await3Result[User, float64, io.Void]]
 
 	P := &io.PromiseImpl[io.Void]{}
+	P.Debug = "Demo"
 	P.Func = func(resolve func(io.Void, error)) {
 		for {
 			switch P.Prev = P.Next; P.Prev {
 			case 0:
-				state1 = GetUserCompiled("123")
 				P.Next = 1
+				state1 = GetUserCompiled("1")
+				state1.Exec = P.Exec
+				state1.Call()
 				return
 			case 1:
-				state1.EnsureDone()
+				if !state1.Done() {
+					state1.Call()
+					return
+				}
+				P.Next = 2
 				user, err := state1.Value, state1.Err
 				log.Printf("user: %v, err: %v\n", user, err)
 
-				state2 = io.Race[User](GetUserCompiled("123"), GetUserCompiled("456"), GetUserCompiled("789"))
-				P.Next = 2
+				state2 = io.Race[User](GetUserCompiled("2"), GetUserCompiled("3"), GetUserCompiled("4"))
+				log.Printf("state2: %v\n", state2)
+				state2.Exec = P.Exec
+				state2.Call()
 				return
 			case 2:
-				state2.EnsureDone()
-				user, err := state2.Value, state2.Err
-				log.Println(user, err)
 
-				state3 = io.All[User]([]io.AsyncCall[User]{GetUserCompiled("123"), GetUserCompiled("456"), GetUserCompiled("789")})
+				if !state2.Done() {
+					state2.Call()
+					return
+				}
+				log.Printf("case 2, state2: %+v\n", state2)
+
 				P.Next = 3
+				user, err := state2.Value, state2.Err
+				log.Printf("race user: %v, err: %v\n", user, err)
+
+				state3 = io.All[User]([]io.AsyncCall[User]{GetUserCompiled("5"), GetUserCompiled("6"), GetUserCompiled("7")})
+				log.Printf("state3: %v\n", state3)
+				state3.Exec = P.Exec
+				state3.Call()
 				return
 			case 3:
-				state3.EnsureDone()
+				if !state3.Done() {
+					state3.Call()
+					return
+				}
+
+				P.Next = 4
 				users, err := state3.Value, state3.Err
 				log.Println(users, err)
 
-				state4 = io.Await3Compiled[User, float64, io.Void](GetUserCompiled("123"), GetScoreCompiled(), DoUpdateCompiled("update sth."))
-				P.Next = 4
+				state4 = io.Await3Compiled[User, float64, io.Void](GetUserCompiled("8"), GetScoreCompiled(), DoUpdateCompiled("update sth."))
+				log.Printf("state4: %v\n", state4)
+				state4.Exec = P.Exec
+				state4.Call()
 				return
 			case 4:
-				state4.EnsureDone()
+				if !state4.Done() {
+					state4.Call()
+					return
+				}
+
+				P.Next = -1
 				user, score, _, err := state4.Value.V1, state4.Value.V2, state4.Value.V3, state4.Value.Err
 				log.Println(user, score, err)
-
-				select {
-				case user := <-GetUserCompiled("123").Chan():
-					log.Println("user:", user)
-				case score := <-GetScoreCompiled().Chan():
-					log.Println("score:", score)
-				case <-io.TimeoutCompiled(5 * time.Second).Chan():
-					log.Println("timeout")
-				}
-				P.Next = -1
+				resolve(io.Void{}, nil)
 				return
 			default:
 				panic("Promise already done")
@@ -286,5 +463,6 @@ func DemoCompiled() *io.PromiseImpl[io.Void] {
 func main() {
 	log.SetFlags(log.Lshortfile | log.LstdFlags)
 	// io.Run(Demo())
-	io.Run(DemoCompiled())
+	v, err := io.Run[io.Void](DemoCompiled())
+	log.Println(v, err)
 }
diff --git a/x/io/extra.go b/x/io/extra.go
new file mode 100644
index 00000000..afd0d72c
--- /dev/null
+++ b/x/io/extra.go
@@ -0,0 +1,177 @@
+/*
+ * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io
+
+import (
+	"log"
+	"sync"
+	"time"
+	_ "unsafe"
+)
+
+// -----------------------------------------------------------------------------
+
+// llgo:link AsyncCall.Await llgo.await
+func Await[OutT any](call AsyncCall[OutT], timeout ...time.Duration) (ret OutT, err error) {
+	return
+}
+
+//go:linkname Timeout llgo.timeout
+func Timeout(time.Duration) (ret AsyncCall[Void])
+
+func TimeoutCompiled(d time.Duration) *PromiseImpl[Void] {
+	P := &PromiseImpl[Void]{}
+	P.Debug = "Timeout"
+	P.Func = func(resolve func(Void, error)) {
+		go func() {
+			time.Sleep(d)
+			resolve(Void{}, nil)
+		}()
+	}
+	return P
+}
+
+type Result[T any] struct {
+	V   T
+	Err error
+}
+
+// llgo:link Race llgo.race
+func Race[OutT any](acs ...AsyncCall[OutT]) *PromiseImpl[OutT] {
+	P := &PromiseImpl[OutT]{}
+	P.Debug = "Race"
+	P.Func = func(resolve func(OutT, error)) {
+		P.Next = -1
+		rc := make(chan Result[OutT], len(acs))
+		for _, ac := range acs {
+			ac := ac
+			go func(ac AsyncCall[OutT]) {
+				v, err := Run(ac)
+				rc <- Result[OutT]{v, err}
+			}(ac)
+		}
+
+		v := <-rc
+		if debugAsync {
+			log.Printf("io.Race done: %+v won the race\n", v)
+		}
+		resolve(v.V, v.Err)
+		go func() {
+			count := 1
+			for count < len(acs) {
+				<-rc
+				count++
+			}
+			close(rc)
+		}()
+	}
+	return P
+}
+
+func All[OutT any](acs []AsyncCall[OutT]) *PromiseImpl[[]Result[OutT]] {
+	P := &PromiseImpl[[]Result[OutT]]{}
+	P.Debug = "All"
+	P.Func = func(resolve func([]Result[OutT], error)) {
+		P.Next = -1
+		wg := sync.WaitGroup{}
+		ret := make([]Result[OutT], len(acs))
+		for idx, ac := range acs {
+			idx := idx
+			ac := ac
+			wg.Add(1)
+			go func(ac AsyncCall[OutT]) {
+				v, err := Run(ac)
+				ret[idx] = Result[OutT]{v, err}
+				wg.Done()
+			}(ac)
+		}
+
+		wg.Wait()
+		if debugAsync {
+			log.Printf("io.All done: %+v\n", ret)
+		}
+		resolve(ret, nil)
+	}
+	return P
+}
+
+// llgo:link Await2 llgo.await
+func Await2[OutT1, OutT2 any](
+	ac1 AsyncCall[OutT1], ac2 AsyncCall[OutT2],
+	timeout ...time.Duration) (ret1 OutT1, ret2 OutT2, err error) {
+	return
+}
+
+type Await2Result[T1 any, T2 any] struct {
+	V1  T1
+	V2  T2
+	Err error
+}
+
+func Await2Compiled[OutT1, OutT2 any](
+	ac1 AsyncCall[OutT1], ac2 AsyncCall[OutT2],
+	timeout ...time.Duration) (ret *PromiseImpl[Await2Result[OutT1, OutT2]]) {
+	return
+}
+
+// llgo:link Await3 llgo.await
+func Await3[OutT1, OutT2, OutT3 any](
+	ac1 AsyncCall[OutT1], ac2 AsyncCall[OutT2], ac3 AsyncCall[OutT3],
+	timeout ...time.Duration) (ret1 OutT1, ret2 OutT2, ret3 OutT3, err error) {
+	return
+}
+
+type Await3Result[T1 any, T2 any, T3 any] struct {
+	V1  T1
+	V2  T2
+	V3  T3
+	Err error
+}
+
+// TODO(lijie): rewrite to unblock and avoid goroutine
+func Await3Compiled[OutT1, OutT2, OutT3 any](
+	ac1 AsyncCall[OutT1], ac2 AsyncCall[OutT2], ac3 AsyncCall[OutT3],
+	timeout ...time.Duration) *PromiseImpl[Await3Result[OutT1, OutT2, OutT3]] {
+	P := &PromiseImpl[Await3Result[OutT1, OutT2, OutT3]]{}
+	P.Debug = "Await3"
+	P.Func = func(resolve func(Await3Result[OutT1, OutT2, OutT3], error)) {
+		P.Next = -1
+
+		ret := Await3Result[OutT1, OutT2, OutT3]{}
+		wg := sync.WaitGroup{}
+		wg.Add(3)
+
+		go func() {
+			defer wg.Done()
+			ret.V1, ret.Err = Run(ac1)
+		}()
+		go func() {
+			defer wg.Done()
+			ret.V2, ret.Err = Run(ac2)
+		}()
+		go func() {
+			defer wg.Done()
+			ret.V3, ret.Err = Run(ac3)
+		}()
+		wg.Wait()
+		if debugAsync {
+			log.Printf("Await3 done: %+v\n", ret)
+		}
+		resolve(ret, nil)
+	}
+	return P
+}
diff --git a/x/io/io.go b/x/io/io.go
index f4b4c18b..f116ad93 100644
--- a/x/io/io.go
+++ b/x/io/io.go
@@ -17,6 +17,8 @@
 package io
 
 import (
+	"log"
+	"sync"
 	_ "unsafe"
 
 	"time"
@@ -26,87 +28,62 @@ const (
 	LLGoPackage = "decl"
 )
 
+var debugAsync = false
+
 type Void = [0]byte
 
 // -----------------------------------------------------------------------------
 
+type asyncCall interface {
+	Resume()
+	Call()
+	Done() bool
+}
+
 type AsyncCall[OutT any] interface {
+	Call()
 	Await(timeout ...time.Duration) (ret OutT, err error)
 	Chan() <-chan OutT
-	EnsureDone()
+	Done() bool
 }
 
-// llgo:link AsyncCall.Await llgo.await
-func Await[OutT any](call AsyncCall[OutT], timeout ...time.Duration) (ret OutT, err error) {
-	return
+type executor struct {
+	ac   asyncCall
+	mu   sync.Mutex
+	cond *sync.Cond
+	susp bool
 }
 
-//go:linkname Timeout llgo.timeout
-func Timeout(time.Duration) (ret AsyncCall[Void])
+func newExecutor() *executor {
+	e := &executor{}
+	e.cond = sync.NewCond(&e.mu)
+	return e
+}
 
-func TimeoutCompiled(d time.Duration) *PromiseImpl[Void] {
-	P := &PromiseImpl[Void]{}
-	P.Func = func(resolve func(Void, error)) {
-		go func() {
-			time.Sleep(d)
-			resolve(Void{}, nil)
-		}()
+func (e *executor) Resume() {
+	e.mu.Lock()
+	defer e.mu.Unlock()
+	e.susp = false
+	e.cond.Signal()
+}
+
+func Run[OutT any](ac AsyncCall[OutT]) (OutT, error) {
+	e := newExecutor()
+	p := ac.(*PromiseImpl[OutT])
+	p.Exec = e
+
+	for {
+		e.mu.Lock()
+		for e.susp {
+			e.cond.Wait()
+		}
+		e.mu.Unlock()
+		e.susp = true
+		if ac.Done() {
+			return p.Value, p.Err
+		}
+		ac.Call()
 	}
-	return P
-}
-
-// llgo:link Race llgo.race
-func Race[OutT any](acs ...AsyncCall[OutT]) (ret *PromiseImpl[OutT]) {
-	return
-}
-
-func All[OutT any](acs []AsyncCall[OutT]) (ret *PromiseImpl[[]OutT]) {
-	return nil
-}
-
-// llgo:link Await2 llgo.await
-func Await2[OutT1, OutT2 any](
-	ac1 AsyncCall[OutT1], ac2 AsyncCall[OutT2],
-	timeout ...time.Duration) (ret1 OutT1, ret2 OutT2, err error) {
-	return
-}
-
-type Await2Result[T1 any, T2 any] struct {
-	V1  T1
-	V2  T2
-	Err error
-}
-
-func Await2Compiled[OutT1, OutT2 any](
-	ac1 AsyncCall[OutT1], ac2 AsyncCall[OutT2],
-	timeout ...time.Duration) (ret *PromiseImpl[Await2Result[OutT1, OutT2]]) {
-	return
-}
-
-// llgo:link Await3 llgo.await
-func Await3[OutT1, OutT2, OutT3 any](
-	ac1 AsyncCall[OutT1], ac2 AsyncCall[OutT2], ac3 AsyncCall[OutT3],
-	timeout ...time.Duration) (ret1 OutT1, ret2 OutT2, ret3 OutT3, err error) {
-	return
-}
-
-type Await3Result[T1 any, T2 any, T3 any] struct {
-	V1  T1
-	V2  T2
-	V3  T3
-	Err error
-}
-
-func Await3Compiled[OutT1, OutT2, OutT3 any](
-	ac1 AsyncCall[OutT1], ac2 AsyncCall[OutT2], ac3 AsyncCall[OutT3],
-	timeout ...time.Duration) (ret *PromiseImpl[Await3Result[OutT1, OutT2, OutT3]]) {
-	return
-}
-
-func Run(ac AsyncCall[Void]) {
-	p := ac.(*PromiseImpl[Void])
-	p.Resume()
-	<-ac.Chan()
 }
 
 // -----------------------------------------------------------------------------
@@ -118,37 +95,49 @@ func (p Promise[OutT]) Await(timeout ...time.Duration) (ret OutT, err error) {
 	return
 }
 
+func (p Promise[OutT]) Call() {
+
+}
+
 func (p Promise[OutT]) Chan() <-chan OutT {
 	return nil
 }
 
-func (p Promise[OutT]) EnsureDone() {
-
+func (p Promise[OutT]) Done() bool {
+	return false
 }
 
 // -----------------------------------------------------------------------------
 
 type PromiseImpl[TOut any] struct {
-	Func  func(resolve func(TOut, error))
-	Value TOut
-	Err   error
 	Prev  int
 	Next  int
+	Exec  *executor
+	Debug string
 
-	c chan TOut
+	Func  func(resolve func(TOut, error))
+	Err   error
+	Value TOut
+	c     chan TOut
 }
 
 func (p *PromiseImpl[TOut]) Resume() {
-	p.Func(func(v TOut, err error) {
-		p.Value = v
-		p.Err = err
-	})
+	p.Exec.Resume()
 }
 
-func (p *PromiseImpl[TOut]) EnsureDone() {
-	if p.Next == -1 {
-		panic("Promise already done")
-	}
+func (p *PromiseImpl[TOut]) Done() bool {
+	return p.Next == -1
+}
+
+func (p *PromiseImpl[TOut]) Call() {
+	p.Func(func(v TOut, err error) {
+		if debugAsync {
+			log.Printf("Resolve task: %+v, %+v, %+v\n", p, v, err)
+		}
+		p.Value = v
+		p.Err = err
+		p.Resume()
+	})
 }
 
 func (p *PromiseImpl[TOut]) Chan() <-chan TOut {