Add foldl and foldr aliases to Foldable

typelevel · Nov 7, 2017 · 138bb6f · 138bb6f
1 parent 6652845
commit 138bb6f
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diff --git a/core/src/main/scala/cats/syntax/foldable.scala b/core/src/main/scala/cats/syntax/foldable.scala
@@ -4,6 +4,9 @@ package syntax
 trait FoldableSyntax extends Foldable.ToFoldableOps {
   implicit final def catsSyntaxNestedFoldable[F[_]: Foldable, G[_], A](fga: F[G[A]]): NestedFoldableOps[F, G, A] =
     new NestedFoldableOps[F, G, A](fga)
+
+  implicit final def catsSyntaxFoldOps[F[_]: Foldable, A](fa: F[A]): FoldableOps[F, A] =
+    new FoldableOps[F, A](fa)
 }
 
 final class NestedFoldableOps[F[_], G[_], A](val fga: F[G[A]]) extends AnyVal {
@@ -23,3 +26,11 @@ final class NestedFoldableOps[F[_], G[_], A](val fga: F[G[A]]) extends AnyVal {
    */
   def foldK(implicit F: Foldable[F], G: MonoidK[G]): G[A] = F.foldK(fga)
 }
+
+final class FoldableOps[F[_], A](val fa: F[A]) extends AnyVal {
+  def foldl[B](b: B)(f: (B, A) => B)(implicit F: Foldable[F]): B =
+    F.foldLeft(fa, b)(f)
+
+  def foldr[B](b: Eval[B])(f: (A, Eval[B]) => Eval[B])(implicit F: Foldable[F]): Eval[B] =
+    F.foldRight(fa, b)(f)
+}
diff --git a/tests/src/test/scala/cats/tests/SyntaxSuite.scala b/tests/src/test/scala/cats/tests/SyntaxSuite.scala
@@ -103,10 +103,12 @@ object SyntaxSuite extends AllInstances with AllSyntax {
     val b = mock[B]
     val f1 = mock[(B, A) => B]
     val b0: B = fa.foldLeft(b)(f1)
+    val b1: B = fa.foldl(b)(f1)
     val a0: A = fa.fold
 
     val f2 = mock[(A, Eval[B]) => Eval[B]]
     val lb0: Eval[B] = fa.foldRight(Now(b))(f2)
+    val lb1: Eval[B] = fa.foldr(Now(b))(f2)
 
     val fz = mock[F[Z]]
     val f3 = mock[Z => A]