Fixed #269 - Add DivariantSyntax and DivariantOps (#270)

Author: ciuncan

src/main/scala/zio/prelude/Divariant.scala

@@ -31,3 +31,20 @@ object Divariant {
     }
   }
 }
+
+trait DivariantSyntax {
+
+  implicit class DivariantOps[:=>[-_, +_], A, B](f: => A :=> B) {
+
+    def dimap[C, D](g: C => A, h: B => D)(implicit divariant: Divariant[:=>]): C :=> D =
+      divariant.dimap(g, h)(f)
+
+    def leftMap[C](ca: C => A)(implicit divariant: Divariant[:=>]): C :=> B =
+      divariant.leftMap(ca)(f)
+
+    def rightMap[C](bc: B => C)(implicit divariant: Divariant[:=>]): A :=> C =
+      divariant.rightMap(bc)(f)
+
+  }
+
+}

src/main/scala/zio/prelude/package.scala

@@ -16,6 +16,7 @@ package object prelude
     with CovariantSyntax
     with ContravariantSyntax
     with DebugSyntax
+    with DivariantSyntax
     with EqualSyntax
     with HashSyntax
     with IdExports