feature/add fold* to EitherOps (#1234)

* feature/add fold* to EitherOps * feature/add fold* to EitherOps * feature/add test case with None --------- Co-authored-by: Igor Fedorov <[email protected]>
tofu-tf · Apr 9, 2024 · 1c3699f · 1c3699f
1 parent f4e5623
commit 1c3699f
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diff --git a/modules/core/ce2/src/test/scala/tofu/syntax/FEitherSuite.scala b/modules/core/ce2/src/test/scala/tofu/syntax/FEitherSuite.scala
@@ -406,6 +406,31 @@ class FEitherSuite extends AnyWordSpec with Matchers {
     }
   }
 
+  "EitherFOps#foldIn" should {
+    "map left or right to C" in {
+      defaultRight.foldIn(_.length, c => c * c) mustBe Some(16)
+      defaultLeft.foldIn(c => c * c, _.length) mustBe Some(16)
+    }
+  }
+
+  "EitherFOps#foldF" should {
+    "map left or right to F[C]" in {
+      defaultRight.foldF(s => Some(s.length), c => Some(c * c)) mustBe Some(16)
+      defaultLeft.foldF(c => Some(c * c), s => Some(s.length)) mustBe Some(16)
+    }
+
+    "fold to None" in {
+      defaultRight.foldF(_ => None, _ => None) mustBe None
+      defaultLeft.foldF(_ => None, _ => None) mustBe None
+    }
+
+    "fold on None" in {
+      val emptyF = Option.empty[Either[String, Int]]
+      emptyF.foldF(_ => None, _ => None) mustBe None
+      emptyF.foldIn(_ => 1, _ => 1) mustBe None
+    }
+  }
+
   "EitherFOps#ensure" should {
 
     "return None" in {

diff --git a/modules/kernel/src/main/scala/tofu/syntax/feither.scala b/modules/kernel/src/main/scala/tofu/syntax/feither.scala
@@ -104,6 +104,14 @@ object feither {
       e.flatMap(_.wideLeft[L1].flatTraverse(f))
     }
 
+    def foldIn[C](lMap: L => C, rMap: R => C)(implicit F: Functor[F]): F[C] = {
+      e.map(_.fold(lMap, rMap))
+    }
+
+    def foldF[C](lMap: L => F[C], rMap: R => F[C])(implicit F: Monad[F]): F[C] = {
+      e.flatMap(_.fold(lMap, rMap))
+    }
+
     def swapF(implicit F: Functor[F]): F[Either[R, L]] = {
       F.map(e)(_.swap)
     }