fmt

typelevel · May 3, 2019 · 64283ce · 64283ce
1 parent ea2401f
commit 64283ce
Show file tree

Hide file tree

Showing 2 changed files with 8 additions and 1 deletion.
diff --git a/core/src/main/scala/cats/Apply.scala b/core/src/main/scala/cats/Apply.scala
@@ -216,6 +216,13 @@ trait Apply[F[_]] extends Functor[F] with InvariantSemigroupal[F] with ApplyArit
 }
 
 object Apply {
+
+  /**
+   * This semigroup uses a product operation to combine `F`s,
+   * if the `Apply[F].product` result in larger `F` e.g. when `F` is a `List`,
+   * accumulative usage of this instance, such as `combineAll`, will result in
+   * `F`s with exponentially increasing sizes.
+   */
   def semigroup[F[_], A](implicit f: Apply[F], sg: Semigroup[A]): Semigroup[F[A]] =
     new ApplySemigroup[F, A](f, sg)
 }

diff --git a/tests/src/test/scala/cats/tests/ApplicativeSuite.scala b/tests/src/test/scala/cats/tests/ApplicativeSuite.scala
@@ -49,7 +49,7 @@ class ApplicativeSuite extends CatsSuite {
     val optionSemigroupFromApply = Apply.semigroup[Option, Int]
     checkAll("Apply[Option].semigroup", SemigroupTests[Option[Int]](optionSemigroupFromApply).semigroup)
   }
-  
+
   {
     implicit val listwrapperApplicative = ListWrapper.applicative
     implicit val listwrapperCoflatMap = Applicative.coflatMap[ListWrapper]