Merge pull request #2860 from bplommer/invariantops-doc

Improve description of InvariantOps
typelevel · Mar 29, 2022 · 5f69848 · 5f69848
2 parents 652b021 + b4f52a8
commit 5f69848
Showing 1 changed file with 4 additions and 1 deletion.
diff --git a/core/shared/src/main/scala/fs2/Stream.scala b/core/shared/src/main/scala/fs2/Stream.scala
@@ -3790,7 +3790,10 @@ object Stream extends StreamLowPriority {
       )(s)
       .stream
 
-  /** Provides syntax for streams that are invariant in `F` and `O`. */
+  /** A view of `Stream` that removes the variance from the type parameters. This allows
+    * defining syntax in which the type parameters appear in contravariant (i.e. input)
+    * position, which would fail to compile if defined as instance methods.
+    */
   implicit final class InvariantOps[F[_], O](private val self: Stream[F, O]) extends AnyVal {
 
     /** Lifts this stream to the specified effect type.