add Future.Then

x/async/async_llgo.go

@@ -53,7 +53,7 @@ func Race[T1 any](futures ...Future[T1]) Future[T1] {
 	return Async(func(resolve func(T1)) {
 		done := atomic.Bool{}
 		for _, future := range futures {
-			future(func(v T1) {
+			future.Then(func(v T1) {
 				if !done.Swap(true) {
 					// Just resolve the first one.
 					resolve(v)
@@ -70,7 +70,7 @@ func All[T1 any](futures ...Future[T1]) Future[[]T1] {
 		var done uint32
 		for i, future := range futures {
 			i := i
-			future(func(v T1) {
+			future.Then(func(v T1) {
 				results[i] = v
 				if atomic.AddUint32(&done, 1) == uint32(n) {
 					// All done.