Merge pull request #80 from gdiet/topic/Option-specialized-tapEach

Specialised Option.tapEach to preserve the type

Author: julienrf

src/main/scala/scala/next/package.scala

@@ -0,0 +1,25 @@
+/*
+ * Scala (https://www.scala-lang.org)
+ *
+ * Copyright EPFL and Lightbend, Inc.
+ *
+ * Licensed under Apache License 2.0
+ * (http://www.apache.org/licenses/LICENSE-2.0).
+ *
+ * See the NOTICE file distributed with this work for
+ * additional information regarding copyright ownership.
+ */
+
+package scala
+
+package object next {
+  implicit final class OptionOpsExtensions[A](private val v: Option[A]) extends AnyVal {
+    /** Apply the side-effecting function `f` to the option's value
+     *  if it is nonempty. Otherwise, do nothing.
+     *
+     *  @param  f  a function to apply to the option's value
+     *  @return the option
+     */
+    def tapEach[B](f: A => B): Option[A] = { v.foreach(f); v }
+  }
+}

src/test/scala/scala/test/TestOptionOpsExtensions.scala

@@ -0,0 +1,24 @@
+/*
+ * Scala (https://www.scala-lang.org)
+ *
+ * Copyright EPFL and Lightbend, Inc.
+ *
+ * Licensed under Apache License 2.0
+ * (http://www.apache.org/licenses/LICENSE-2.0).
+ *
+ * See the NOTICE file distributed with this work for
+ * additional information regarding copyright ownership.
+ */
+
+package scala.test
+
+import scala.next._
+
+final class TestOptionOpsExtensions {
+  // Compile checks the return type, no need to run as test.
+  def tapEachReturnType(): Option[Int] = {
+    // Don't return the option directly, so the compiler is not able to coerce a specific implicit to be used.
+    val opt = Option(5).tapEach(identity)
+    opt.map(identity)
+  }
+}