✨ Add flatTapIn and flatTapF to FOptionSyntax and FEitherSyntax

typelevel · Apr 17, 2024 · 30f35c6 · 30f35c6
1 parent dfb9557
commit 30f35c6
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diff --git a/shared/src/main/scala/mouse/feither.scala b/shared/src/main/scala/mouse/feither.scala
@@ -54,6 +54,12 @@ final class FEitherOps[F[_], L, R](private val felr: F[Either[L, R]]) extends An
       case Right(value) => f(value)
     }
 
+  def flatTapIn[A >: L, B](f: R => Either[A, B])(implicit F: Functor[F]): F[Either[A, R]] =
+    flatMapIn(value => f(value).map(_ => value))
+
+  def flatTapF[A >: L, B](f: R => F[Either[A, B]])(implicit F: Monad[F]): F[Either[A, R]] =
+    flatMapF(value => F.map(f(value))(_.map(_ => value)))
+
   def foldIn[A](left: L => A)(right: R => A)(implicit F: Functor[F]): F[A] =
     cata(left, right)
 

diff --git a/shared/src/main/scala/mouse/foption.scala b/shared/src/main/scala/mouse/foption.scala
@@ -73,6 +73,12 @@ final class FOptionOps[F[_], A](private val foa: F[Option[A]]) extends AnyVal {
   def flatMapF[B](f: A => F[Option[B]])(implicit F: Monad[F]): F[Option[B]] =
     F.flatMap(foa)(_.fold(F.pure(Option.empty[B]))(f))
 
+  def flatTapIn[B](f: A => Option[B])(implicit F: Functor[F]): F[Option[A]] =
+    flatMapIn(value => f(value).map(_ => value))
+
+  def flatTapF[B](f: A => F[Option[B]])(implicit F: Monad[F]): F[Option[A]] =
+    flatMapF { value => F.map(f(value))(_.map(_ => value)) }
+
   def foldIn[B](default: => B)(f: A => B)(implicit F: Functor[F]): F[B] =
     cata(default, f)
 

diff --git a/shared/src/test/scala/mouse/FEitherSyntaxTest.scala b/shared/src/test/scala/mouse/FEitherSyntaxTest.scala
@@ -57,6 +57,16 @@ class FEitherSyntaxTest extends MouseSuite {
     assertEquals(leftValue.flatMapF(i => List((i * 2).asRight[String])), leftValue)
   }
 
+  test("FEitherSyntax.flatTapIn") {
+    assertEquals(rightValue.flatTapIn(i => (i * 2).asRight[String]), List(42.asRight[String]))
+    assertEquals(leftValue.flatTapIn(i => (i * 2).asRight[String]), leftValue)
+  }
+
+  test("FEitherSyntax.flatTapF") {
+    assertEquals(rightValue.flatTapF(i => List((i * 2).asRight[String])), List(42.asRight[String]))
+    assertEquals(leftValue.flatTapF(i => List((i * 2).asRight[String])), leftValue)
+  }
+
   test("FEitherSyntax.foldIn") {
     assertEquals(rightValue.foldIn(_ => 0)(_ => 1), List(1))
     assertEquals(leftValue.foldIn(_ => 0)(_ => 1), List(0))

diff --git a/shared/src/test/scala/mouse/FOptionSyntaxTest.scala b/shared/src/test/scala/mouse/FOptionSyntaxTest.scala
@@ -72,6 +72,16 @@ class FOptionSyntaxTest extends MouseSuite {
     assertEquals(List(Option.empty[Int]).flatMapF(a => List(Option(a * 2))), List(Option.empty[Int]))
   }
 
+  test("FOptionSyntax.flatTapIn") {
+    assertEquals(List(Option(1)).flatTapIn(a => Option(a * 2)), List(Option(1)))
+    assertEquals(List(Option.empty[Int]).flatTapIn(a => Option(a * 2)), List(Option.empty[Int]))
+  }
+
+  test("FOptionSyntax.flatMapF") {
+    assertEquals(List(Option(1)).flatTapF(a => List(Option(a * 2))), List(Option(1)))
+    assertEquals(List(Option.empty[Int]).flatTapF(a => List(Option(a * 2))), List(Option.empty[Int]))
+  }
+
   test("FOptionSyntax.foldIn") {
     assertEquals(List(Option(1)).foldIn(false)(_ => true), List(true))
     assertEquals(List(Option.empty[Int]).foldIn(false)(_ => true), List(false))