From 30f35c655a8b7b8df2b049b84fa2fe29b0ae34c3 Mon Sep 17 00:00:00 2001
From: Jakub Wojnowski <29680262+jwojnowski@users.noreply.github.com>
Date: Wed, 17 Apr 2024 17:04:55 +0200
Subject: [PATCH] =?UTF-8?q?=E2=9C=A8=20Add=20`flatTapIn`=20and=20`flatTapF?=
 =?UTF-8?q?`=20to=20`FOptionSyntax`=20and=20`FEitherSyntax`?=
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---
 shared/src/main/scala/mouse/feither.scala           |  6 ++++++
 shared/src/main/scala/mouse/foption.scala           |  6 ++++++
 shared/src/test/scala/mouse/FEitherSyntaxTest.scala | 10 ++++++++++
 shared/src/test/scala/mouse/FOptionSyntaxTest.scala | 10 ++++++++++
 4 files changed, 32 insertions(+)

diff --git a/shared/src/main/scala/mouse/feither.scala b/shared/src/main/scala/mouse/feither.scala
index e2f9f54..9aed308 100644
--- 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
index 781d0a7..44e0ebc 100644
--- 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
index 29b2144..e9bd616 100644
--- 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
index d640bb1..b80b102 100644
--- 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))