Merge pull request #4036 from BalmungSan/patch-1

Adding Id.apply
typelevel · Nov 6, 2021 · 6a6d4e4 · 6a6d4e4
2 parents 1a7b9d8 + 7270f8f
commit 6a6d4e4
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diff --git a/core/src/main/scala/cats/package.scala b/core/src/main/scala/cats/package.scala
@@ -64,6 +64,10 @@ package object cats {
    * encodes pure unary function application.
    */
   type Id[A] = A
+  object Id {
+    def apply[A](a: A): Id[A] = a
+  }
+
   type Endo[A] = A => A
 
   val catsInstancesForId: Bimonad[Id] with CommutativeMonad[Id] with NonEmptyTraverse[Id] with Distributive[Id] =

diff --git a/tests/src/test/scala/cats/tests/IdSuite.scala b/tests/src/test/scala/cats/tests/IdSuite.scala
@@ -2,6 +2,9 @@ package cats.tests
 
 import cats.{Bimonad, CommutativeMonad, Id, Reducible, Traverse}
 import cats.laws.discipline._
+import cats.syntax.applicative._
+import cats.syntax.eq._
+import org.scalacheck.Prop._
 
 class IdSuite extends CatsSuite {
   implicit val iso: SemigroupalTests.Isomorphisms[Id] =
@@ -18,4 +21,13 @@ class IdSuite extends CatsSuite {
 
   checkAll("Id[Int]", ReducibleTests[Id].reducible[Option, Int, Int])
   checkAll("Reducible[Id]", SerializableTests.serializable(Reducible[Id]))
+
+  test("Id#apply") {
+    forAll { (i: Int) =>
+      val id = Id(i)
+      assert(id === (i: Id[Int]))
+      assert(id === i.pure[Id])
+      assert(id === i)
+    }
+  }
 }