Merge pull request #4662 from m50d/unorderedfoldmapm

Add `unorderedFoldMapA` method
typelevel · Oct 10, 2024 · 478e1a4 · 478e1a4
2 parents 0bb930f + 2fd1efd
commit 478e1a4
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Showing 3 changed files with 29 additions and 1 deletion.
diff --git a/core/src/main/scala/cats/UnorderedFoldable.scala b/core/src/main/scala/cats/UnorderedFoldable.scala
@@ -35,6 +35,27 @@ trait UnorderedFoldable[F[_]] extends Serializable {
   def unorderedFold[A: CommutativeMonoid](fa: F[A]): A =
     unorderedFoldMap(fa)(identity)
 
+  /**
+   * Fold in a [[CommutativeApplicative]] context by mapping the `A` values to `G[B]`. combining
+   * the `B` values using the given `CommutativeMonoid[B]` instance.
+   *
+   * {{{
+   * scala> import cats.UnorderedFoldable
+   * scala> import cats.syntax.all._
+   * scala> val evenNumbers = Set(2,4,6,8,10)
+   * scala> val evenOpt: Int => Option[Int] =
+   *      |   i => if (i % 2 == 0) Some(i) else None
+   * scala> UnorderedFoldable[Set].unorderedFoldMapA(evenNumbers)(evenOpt)
+   * res0: Option[Int] = Some(30)
+   * scala> UnorderedFoldable[Set].unorderedFoldMapA(evenNumbers + 11)(evenOpt)
+   * res1: Option[Int] = None
+   * }}}
+   */
+  def unorderedFoldMapA[G[_], A, B](fa: F[A])(
+    f: A => G[B]
+  )(implicit G: CommutativeApplicative[G], B: CommutativeMonoid[B]): G[B] =
+    unorderedFoldMap(fa)(f)(CommutativeApplicative.commutativeMonoidFor)
+
   /**
    * Tests if `fa` contains `v` using the `Eq` instance for `A`
    */
@@ -170,6 +191,10 @@ object UnorderedFoldable
     def unorderedFoldMap[B](f: A => B)(implicit ev$1: CommutativeMonoid[B]): B =
       typeClassInstance.unorderedFoldMap[A, B](self)(f)
     def unorderedFold(implicit ev$1: CommutativeMonoid[A]): A = typeClassInstance.unorderedFold[A](self)
+    def unorderedFoldMapA[G[_], B](
+      f: A => G[B]
+    )(implicit ev$1: CommutativeApplicative[G], ev$2: CommutativeMonoid[B]): G[B] =
+      typeClassInstance.unorderedFoldMapA[G, A, B](self)(f)
     def isEmpty: Boolean = typeClassInstance.isEmpty[A](self)
     def nonEmpty: Boolean = typeClassInstance.nonEmpty[A](self)
     def exists(p: A => Boolean): Boolean = typeClassInstance.exists[A](self)(p)
@@ -189,5 +214,4 @@ object UnorderedFoldable
   }
   @deprecated("Use cats.syntax object imports", "2.2.0")
   object nonInheritedOps extends ToUnorderedFoldableOps
-
 }
diff --git a/laws/src/main/scala/cats/laws/UnorderedFoldableLaws.scala b/laws/src/main/scala/cats/laws/UnorderedFoldableLaws.scala
@@ -30,6 +30,9 @@ trait UnorderedFoldableLaws[F[_]] {
   def unorderedFoldConsistentWithUnorderedFoldMap[A: CommutativeMonoid](fa: F[A]): IsEq[A] =
     F.unorderedFoldMap(fa)(identity) <-> F.unorderedFold(fa)
 
+  def unorderedFoldMapAIdentity[A, B: CommutativeMonoid](fa: F[A], f: A => B): IsEq[B] =
+    F.unorderedFoldMapA[Id, A, B](fa)(f) <-> F.unorderedFoldMap(fa)(f)
+
   def forallConsistentWithExists[A](fa: F[A], p: A => Boolean): Boolean =
     if (F.forall(fa)(p)) {
       val negationExists = F.exists(fa)(a => !p(a))

diff --git a/laws/src/main/scala/cats/laws/discipline/UnorderedFoldableTests.scala b/laws/src/main/scala/cats/laws/discipline/UnorderedFoldableTests.scala
@@ -45,6 +45,7 @@ trait UnorderedFoldableTests[F[_]] extends Laws {
       name = "unorderedFoldable",
       parent = None,
       "unorderedFold consistent with unorderedFoldMap" -> forAll(laws.unorderedFoldConsistentWithUnorderedFoldMap[A] _),
+      "unorderedFoldMapA identity" -> forAll(laws.unorderedFoldMapAIdentity[A, B] _),
       "forall consistent with exists" -> forAll(laws.forallConsistentWithExists[A] _),
       "forall true if empty" -> forAll(laws.forallEmpty[A] _),
       "nonEmpty reference" -> forAll(laws.nonEmptyRef[A] _),