Fix typelevel#2236 implement Async.fromThenable

armanbilge · Aug 16, 2021 · 8e0cc4e · 8e0cc4e
1 parent 203e25c
commit 8e0cc4e
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Showing 2 changed files with 9 additions and 4 deletions.
diff --git a/core/js/src/main/scala/cats/effect/IOCompanionPlatform.scala b/core/js/src/main/scala/cats/effect/IOCompanionPlatform.scala
@@ -18,7 +18,7 @@ package cats.effect
 
 import scalajs.js
 
-import scala.scalajs.js.Promise
+import scala.scalajs.js.{Promise, Thenable}
 
 private[effect] abstract class IOCompanionPlatform { this: IO.type =>
 
@@ -35,6 +35,9 @@ private[effect] abstract class IOCompanionPlatform { this: IO.type =>
     apply(thunk)
   }
 
+  def fromThenable[A](iot: IO[Thenable[A]]): IO[A] =
+    asyncForIO.fromThenable(iot)
+
   def fromPromise[A](iop: IO[Promise[A]]): IO[A] =
     asyncForIO.fromPromise(iop)
 

diff --git a/kernel/js/src/main/scala/cats/effect/kernel/AsyncPlatform.scala b/kernel/js/src/main/scala/cats/effect/kernel/AsyncPlatform.scala
@@ -20,8 +20,10 @@ import scala.scalajs.js.{|, defined, Function1, JavaScriptException, Promise, Th
 
 private[kernel] trait AsyncPlatform[F[_]] { this: Async[F] =>
 
-  def fromPromise[A](iop: F[Promise[A]]): F[A] =
-    flatMap(iop) { p =>
+  def fromPromise[A](iop: F[Promise[A]]): F[A] = fromThenable(widen(iop))
+
+  def fromThenable[A](iot: F[Thenable[A]]): F[A] =
+    flatMap(iot) { t =>
       async_[A] { cb =>
         val onFulfilled: Function1[A, Unit | Thenable[Unit]] =
           (v: A) => cb(Right(v)): Unit | Thenable[Unit]
@@ -35,7 +37,7 @@ private[kernel] trait AsyncPlatform[F[_]] { this: Async[F] =>
           cb(Left(e)): Unit | Thenable[Unit]
         }
 
-        p.`then`[Unit](onFulfilled, defined(onRejected))
+        t.`then`[Unit](onFulfilled, defined(onRejected))
 
         ()
       }