Merge pull request #1028 from hntd187/withFilter

Added withFilter for OptionT
typelevel · May 14, 2016 · 3febb06 · 3febb06
2 parents c3a2326 + 2869e7f
commit 3febb06
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diff --git a/core/src/main/scala/cats/data/OptionT.scala b/core/src/main/scala/cats/data/OptionT.scala
@@ -2,7 +2,7 @@ package cats
 package data
 
 /**
- * `OptionT[F[_], A` is a light wrapper on an `F[Option[A]]` with some
+ * `OptionT[F[_], A]` is a light wrapper on an `F[Option[A]]` with some
  * convenient methods for working with this nested structure.
  *
  * It may also be said that `OptionT` is a monad transformer for `Option`.
@@ -59,6 +59,9 @@ final case class OptionT[F[_], A](value: F[Option[A]]) {
   def filter(p: A => Boolean)(implicit F: Functor[F]): OptionT[F, A] =
     OptionT(F.map(value)(_.filter(p)))
 
+  def withFilter(p: A => Boolean)(implicit F: Functor[F]): OptionT[F, A] =
+    filter(p)(F)
+
   def filterNot(p: A => Boolean)(implicit F: Functor[F]): OptionT[F, A] =
     OptionT(F.map(value)(_.filterNot(p)))
 

diff --git a/tests/src/test/scala/cats/tests/OptionTTests.scala b/tests/src/test/scala/cats/tests/OptionTTests.scala
@@ -50,6 +50,12 @@ class OptionTTests extends CatsSuite {
     }
   }
 
+  test("OptionT[Id, A].withFilter consistent with Option.withFilter"){
+    forAll { (o: Option[Int], f: Int => Boolean) =>
+      (for {x <- o if f(x)} yield x) should === ((for {x <- OptionT[Id, Int](o) if f(x)} yield x).value)
+    }
+  }
+
   test("OptionT[Id, A].filterNot consistent with Option.filterNot") {
     forAll { (o: Option[Int], f: Int => Boolean) =>
       o.filterNot(f) should === (OptionT[Id, Int](o).filterNot(f).value)