Add comments, remove redundant syntax extension

typelevel · Aug 11, 2018 · c790418 · c790418
1 parent 2f71ee1
commit c790418
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Showing 3 changed files with 21 additions and 9 deletions.
diff --git a/core/src/main/scala/cats/syntax/all.scala b/core/src/main/scala/cats/syntax/all.scala
@@ -72,4 +72,3 @@ trait AllSyntaxBinCompat1
 
 trait AllSyntaxBinCompat2
   extends ParallelTraverseSyntax
-    with FoldableExtensionSyntax
diff --git a/core/src/main/scala/cats/syntax/foldable.scala b/core/src/main/scala/cats/syntax/foldable.scala
@@ -94,14 +94,27 @@ final class FoldableOps[F[_], A](val fa: F[A]) extends AnyVal {
         b.toString.dropRight(delim.length)
     } + suffix
   }
-}
-
-trait FoldableExtensionSyntax {
-  implicit final def catsSyntaxFoldableExtension[F[_], A](fa: F[A]): FoldableExtension[F, A] =
-    new FoldableExtension(fa)
-}
 
-final class FoldableExtension[F[_], A](val fa: F[A]) extends AnyVal {
+  /**
+    * Monadic version of `collectFirstSome`.
+    * {{{
+    * scala> import cats.implicits._
+    * scala> def parseInt(s: String): Either[String, Int] = Either.catchOnly[NumberFormatException](s.toInt).leftMap(_.getMessage)
+    * scala> val keys1 = List("1", "2", "4", "5")
+    * scala> val map1 = Map(4 -> "Four", 5 -> "Five")
+    * scala> keys1.collectFirstSomeM(parseInt(_) map map1.get)
+    * res1: scala.util.Either[String,Option[String]] = Right(Some(Four))
+    * scala> val map2 = Map(6 -> "Six", 7 -> "Seven")
+    * scala> keys1.collectFirstSomeM(parseInt(_) map map2.get)
+    * res2: scala.util.Either[String,Option[String]] = Right(None)
+    * scala> val keys2 = List("1", "x", "4", "5")
+    * scala> keys2.collectFirstSomeM(parseInt(_) map map1.get)
+    * res3: scala.util.Either[String,Option[String]] = Left(For input string: "x")
+    * scala> val keys3 = List("1", "2", "4", "x")
+    * scala> keys3.collectFirstSomeM(parseInt(_) map map1.get)
+    * res4: scala.util.Either[String,Option[String]] = Right(Some(Four))
+    * }}}
+    */
   def collectFirstSomeM[G[_], B](f: A => G[Option[B]])(implicit F: Foldable[F], G: Monad[G]): G[Option[B]] =
     F.foldRight(fa, Eval.now(OptionT.none[G, B]))((a, lb) =>
       Eval.now(OptionT(f(a)).orElse(lb.value))

diff --git a/core/src/main/scala/cats/syntax/package.scala b/core/src/main/scala/cats/syntax/package.scala
@@ -26,7 +26,7 @@ package object syntax {
   object either extends EitherSyntax
   object eq extends EqSyntax
   object flatMap extends FlatMapSyntax
-  object foldable extends FoldableSyntax with FoldableExtensionSyntax
+  object foldable extends FoldableSyntax
   object functor extends FunctorSyntax
   object group extends GroupSyntax
   object invariant extends InvariantSyntax