Generalized mapAccumM signature #1029 (#1037)

* Generalized mapAccumM signature * Fixed weird compiler error with explicit type parameters
zio · Jun 20, 2019 · 9118819 · 9118819
1 parent ff9cb76
commit 9118819
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Showing 2 changed files with 5 additions and 5 deletions.
diff --git a/streams/jvm/src/test/scala/zio/stream/StreamSpec.scala b/streams/jvm/src/test/scala/zio/stream/StreamSpec.scala
@@ -600,7 +600,7 @@ class ZStreamSpec(implicit ee: org.specs2.concurrent.ExecutionEnv)
   }
 
   private def mapAccumM = {
-    val stream = Stream(1, 1, 1).mapAccumM(0)((acc, el) => IO.succeed((acc + el, acc + el)))
+    val stream = Stream(1, 1, 1).mapAccumM[Any, Nothing, Int, Int](0)((acc, el) => IO.succeed((acc + el, acc + el)))
     (slurp(stream) must_=== Success(List(1, 2, 3))) and (slurp(stream) must_=== Success(List(1, 2, 3)))
   }
 

diff --git a/streams/shared/src/main/scala/zio/stream/ZStream.scala b/streams/shared/src/main/scala/zio/stream/ZStream.scala
@@ -389,11 +389,11 @@ trait ZStream[-R, +E, +A] extends Serializable { self =>
    * Statefully and effectfully maps over the elements of this stream to produce
    * new elements.
    */
-  final def mapAccumM[E1 >: E, S1, B](s1: S1)(f1: (S1, A) => IO[E1, (S1, B)]): ZStream[R, E1, B] =
-    new ZStream[R, E1, B] {
-      override def fold[R1 <: R, E2 >: E1, B1 >: B, S]: Fold[R1, E2, B1, S] =
+  final def mapAccumM[R1 <: R, E1 >: E, S1, B](s1: S1)(f1: (S1, A) => ZIO[R1, E1, (S1, B)]): ZStream[R1, E1, B] =
+    new ZStream[R1, E1, B] {
+      override def fold[R2 <: R1, E2 >: E1, B1 >: B, S]: Fold[R2, E2, B1, S] =
         ZManaged.succeedLazy { (s, cont, f) =>
-          self.fold[R1, E2, A, (S, S1)].flatMap { fold =>
+          self.fold[R2, E2, A, (S, S1)].flatMap { fold =>
             fold(s -> s1, tp => cont(tp._1), {
               case ((s, s1), a) =>
                 f1(s1, a).flatMap {