From 3d8334d5e10b93ce2e33530576f4c875b4a09ce6 Mon Sep 17 00:00:00 2001
From: Patrick Oscar Boykin <boykin@pobox.com>
Date: Tue, 17 Aug 2021 21:27:05 -1000
Subject: [PATCH] override toIterable more and use it

---
 .../src/main/scala/alleycats/std/map.scala    |  2 ++
 .../src/main/scala/alleycats/std/set.scala    |  2 ++
 core/src/main/scala/cats/Composed.scala       |  6 +++++
 core/src/main/scala/cats/Foldable.scala       | 26 +++++++------------
 .../main/scala/cats/data/NonEmptyList.scala   |  2 ++
 .../main/scala/cats/data/NonEmptySeq.scala    |  2 ++
 .../main/scala/cats/data/NonEmptySet.scala    |  2 ++
 .../main/scala/cats/data/NonEmptyVector.scala |  2 ++
 .../main/scala/cats/instances/either.scala    |  7 ++++-
 core/src/main/scala/cats/instances/list.scala |  2 ++
 .../src/main/scala/cats/instances/queue.scala |  2 ++
 core/src/main/scala/cats/instances/seq.scala  |  2 ++
 .../main/scala/cats/instances/sortedMap.scala |  2 ++
 .../main/scala/cats/instances/sortedSet.scala |  2 ++
 .../src/main/scala/cats/instances/tuple.scala |  4 +++
 .../main/scala/cats/instances/vector.scala    |  2 ++
 16 files changed, 49 insertions(+), 18 deletions(-)

diff --git a/alleycats-core/src/main/scala/alleycats/std/map.scala b/alleycats-core/src/main/scala/alleycats/std/map.scala
index d98b669ed3..f26538da61 100644
--- a/alleycats-core/src/main/scala/alleycats/std/map.scala
+++ b/alleycats-core/src/main/scala/alleycats/std/map.scala
@@ -50,6 +50,8 @@ trait MapInstances {
 
       override def toList[A](fa: Map[K, A]): List[A] = fa.values.toList
 
+      override def toIterable[A](fa: Map[K, A]): Iterable[A] = fa.values
+
       override def collectFirst[A, B](fa: Map[K, A])(pf: PartialFunction[A, B]): Option[B] =
         fa.collectFirst(new PartialFunction[(K, A), B] {
           override def isDefinedAt(x: (K, A)) = pf.isDefinedAt(x._2)
diff --git a/alleycats-core/src/main/scala/alleycats/std/set.scala b/alleycats-core/src/main/scala/alleycats/std/set.scala
index 3f763cd87a..af9747b75c 100644
--- a/alleycats-core/src/main/scala/alleycats/std/set.scala
+++ b/alleycats-core/src/main/scala/alleycats/std/set.scala
@@ -122,6 +122,8 @@ trait SetInstances {
 
       override def toList[A](fa: Set[A]): List[A] = fa.toList
 
+      override def toIterable[A](fa: Set[A]): Iterable[A] = fa
+
       override def reduceLeftOption[A](fa: Set[A])(f: (A, A) => A): Option[A] =
         fa.reduceLeftOption(f)
 
diff --git a/core/src/main/scala/cats/Composed.scala b/core/src/main/scala/cats/Composed.scala
index d7722fe918..31c155168e 100644
--- a/core/src/main/scala/cats/Composed.scala
+++ b/core/src/main/scala/cats/Composed.scala
@@ -73,6 +73,12 @@ private[cats] trait ComposedFoldable[F[_], G[_]] extends Foldable[λ[α => F[G[
 
   override def foldRight[A, B](fga: F[G[A]], lb: Eval[B])(f: (A, Eval[B]) => Eval[B]): Eval[B] =
     F.foldRight(fga, lb)((ga, lb) => G.foldRight(ga, lb)(f))
+
+  override def toList[A](fga: F[G[A]]): List[A] =
+    F.toList(fga).flatMap(G.toList)
+
+  override def toIterable[A](fga: F[G[A]]): Iterable[A] =
+    F.toIterable(fga).flatMap(G.toIterable)
 }
 
 private[cats] trait ComposedTraverse[F[_], G[_]]
diff --git a/core/src/main/scala/cats/Foldable.scala b/core/src/main/scala/cats/Foldable.scala
index 9370e24913..7616bd7d76 100644
--- a/core/src/main/scala/cats/Foldable.scala
+++ b/core/src/main/scala/cats/Foldable.scala
@@ -337,11 +337,11 @@ trait Foldable[F[_]] extends UnorderedFoldable[F] with FoldableNFunctions[F] { s
    * res1: Option[String] = None
    * }}}
    */
-  def collectFirstSome[A, B](fa: F[A])(f: A => Option[B]): Option[B] =
-    foldRight(fa, Eval.now(Option.empty[B])) { (a, lb) =>
-      val ob = f(a)
-      if (ob.isDefined) Eval.now(ob) else lb
-    }.value
+  def collectFirstSome[A, B](fa: F[A])(f: A => Option[B]): Option[B] = {
+    val maybeEmpty = toIterable(fa).iterator.map(f).dropWhile(_.isEmpty)
+    if (maybeEmpty.hasNext) maybeEmpty.next()
+    else None
+  }
 
   /**
    * Monadic version of `collectFirstSome`.
@@ -622,9 +622,7 @@ trait Foldable[F[_]] extends UnorderedFoldable[F] with FoldableNFunctions[F] { s
    * Find the first element matching the predicate, if one exists.
    */
   def find[A](fa: F[A])(f: A => Boolean): Option[A] =
-    foldRight(fa, Now(Option.empty[A])) { (a, lb) =>
-      if (f(a)) Now(Some(a)) else lb
-    }.value
+    toIterable(fa).find(f)
 
   /**
    * Find the first element matching the effectful predicate, if one exists.
@@ -662,9 +660,7 @@ trait Foldable[F[_]] extends UnorderedFoldable[F] with FoldableNFunctions[F] { s
    * If there are no elements, the result is `false`.
    */
   override def exists[A](fa: F[A])(p: A => Boolean): Boolean =
-    foldRight(fa, Eval.False) { (a, lb) =>
-      if (p(a)) Eval.True else lb
-    }.value
+    toIterable(fa).exists(p)
 
   /**
    * Check whether all elements satisfy the predicate.
@@ -672,9 +668,7 @@ trait Foldable[F[_]] extends UnorderedFoldable[F] with FoldableNFunctions[F] { s
    * If there are no elements, the result is `true`.
    */
   override def forall[A](fa: F[A])(p: A => Boolean): Boolean =
-    foldRight(fa, Eval.True) { (a, lb) =>
-      if (p(a)) lb else Eval.False
-    }.value
+    toIterable(fa).forall(p)
 
   /**
    * Check whether at least one element satisfies the effectful predicate.
@@ -792,9 +786,7 @@ trait Foldable[F[_]] extends UnorderedFoldable[F] with FoldableNFunctions[F] { s
    * match `p`.
    */
   def takeWhile_[A](fa: F[A])(p: A => Boolean): List[A] =
-    foldRight(fa, Now(List.empty[A])) { (a, llst) =>
-      if (p(a)) llst.map(a :: _) else Now(Nil)
-    }.value
+    toIterable(fa).iterator.takeWhile(p).toList
 
   /**
    * Convert F[A] to a List[A], dropping all initial elements which
diff --git a/core/src/main/scala/cats/data/NonEmptyList.scala b/core/src/main/scala/cats/data/NonEmptyList.scala
index 26944c873e..62612e5f29 100644
--- a/core/src/main/scala/cats/data/NonEmptyList.scala
+++ b/core/src/main/scala/cats/data/NonEmptyList.scala
@@ -825,6 +825,8 @@ sealed abstract private[data] class NonEmptyListInstances extends NonEmptyListIn
 
       override def toList[A](fa: NonEmptyList[A]): List[A] = fa.toList
 
+      override def toIterable[A](fa: NonEmptyList[A]): Iterable[A] = fa.toList
+
       override def toNonEmptyList[A](fa: NonEmptyList[A]): NonEmptyList[A] = fa
 
       override def get[A](fa: NonEmptyList[A])(idx: Long): Option[A] =
diff --git a/core/src/main/scala/cats/data/NonEmptySeq.scala b/core/src/main/scala/cats/data/NonEmptySeq.scala
index 482c7c189d..d15542d0d5 100644
--- a/core/src/main/scala/cats/data/NonEmptySeq.scala
+++ b/core/src/main/scala/cats/data/NonEmptySeq.scala
@@ -477,6 +477,8 @@ sealed abstract private[data] class NonEmptySeqInstances {
 
       override def toList[A](fa: NonEmptySeq[A]): List[A] = fa.toSeq.toList
 
+      override def toIterable[A](fa: NonEmptySeq[A]): Iterable[A] = fa.toSeq
+
       override def toNonEmptyList[A](fa: NonEmptySeq[A]): NonEmptyList[A] =
         NonEmptyList(fa.head, fa.tail.toList)
 
diff --git a/core/src/main/scala/cats/data/NonEmptySet.scala b/core/src/main/scala/cats/data/NonEmptySet.scala
index c55cb34c78..0fc3328ebe 100644
--- a/core/src/main/scala/cats/data/NonEmptySet.scala
+++ b/core/src/main/scala/cats/data/NonEmptySet.scala
@@ -386,6 +386,8 @@ sealed abstract private[data] class NonEmptySetInstances extends NonEmptySetInst
 
       override def toList[A](fa: NonEmptySet[A]): List[A] = fa.toSortedSet.toList
 
+      override def toIterable[A](fa: NonEmptySet[A]): Iterable[A] = fa.toSortedSet
+
       override def toNonEmptyList[A](fa: NonEmptySet[A]): NonEmptyList[A] =
         fa.toNonEmptyList
     }
diff --git a/core/src/main/scala/cats/data/NonEmptyVector.scala b/core/src/main/scala/cats/data/NonEmptyVector.scala
index cfd8d4c33f..bdc9e139e3 100644
--- a/core/src/main/scala/cats/data/NonEmptyVector.scala
+++ b/core/src/main/scala/cats/data/NonEmptyVector.scala
@@ -479,6 +479,8 @@ sealed abstract private[data] class NonEmptyVectorInstances {
 
       override def toList[A](fa: NonEmptyVector[A]): List[A] = fa.toVector.toList
 
+      override def toIterable[A](fa: NonEmptyVector[A]): Iterable[A] = fa.toVector
+
       override def toNonEmptyList[A](fa: NonEmptyVector[A]): NonEmptyList[A] =
         NonEmptyList(fa.head, fa.tail.toList)
 
diff --git a/core/src/main/scala/cats/instances/either.scala b/core/src/main/scala/cats/instances/either.scala
index da03849ad9..8efa5ef581 100644
--- a/core/src/main/scala/cats/instances/either.scala
+++ b/core/src/main/scala/cats/instances/either.scala
@@ -151,7 +151,12 @@ trait EitherInstances extends cats.kernel.instances.EitherInstances {
         fab.forall(p)
 
       override def toList[B](fab: Either[A, B]): List[B] =
-        fab.fold(_ => Nil, _ :: Nil)
+        fab match {
+          case Right(a) => a :: Nil
+          case Left(_)  => Nil
+        }
+
+      override def toIterable[B](fab: Either[A, B]): Iterable[B] = toList(fab)
 
       override def isEmpty[B](fab: Either[A, B]): Boolean =
         fab.isLeft
diff --git a/core/src/main/scala/cats/instances/list.scala b/core/src/main/scala/cats/instances/list.scala
index bcd852d06d..434a916d20 100644
--- a/core/src/main/scala/cats/instances/list.scala
+++ b/core/src/main/scala/cats/instances/list.scala
@@ -202,6 +202,8 @@ trait ListInstances extends cats.kernel.instances.ListInstances {
 
       override def toList[A](fa: List[A]): List[A] = fa
 
+      override def toIterable[A](fa: List[A]): Iterable[A] = fa
+
       override def reduceLeftOption[A](fa: List[A])(f: (A, A) => A): Option[A] =
         fa.reduceLeftOption(f)
 
diff --git a/core/src/main/scala/cats/instances/queue.scala b/core/src/main/scala/cats/instances/queue.scala
index 4466f38293..df2b5d0940 100644
--- a/core/src/main/scala/cats/instances/queue.scala
+++ b/core/src/main/scala/cats/instances/queue.scala
@@ -131,6 +131,8 @@ trait QueueInstances extends cats.kernel.instances.QueueInstances {
 
       override def toList[A](fa: Queue[A]): List[A] = fa.toList
 
+      override def toIterable[A](fa: Queue[A]): Iterable[A] = fa
+
       override def reduceLeftOption[A](fa: Queue[A])(f: (A, A) => A): Option[A] =
         fa.reduceLeftOption(f)
 
diff --git a/core/src/main/scala/cats/instances/seq.scala b/core/src/main/scala/cats/instances/seq.scala
index 0ba777eb44..b8e52d0309 100644
--- a/core/src/main/scala/cats/instances/seq.scala
+++ b/core/src/main/scala/cats/instances/seq.scala
@@ -117,6 +117,8 @@ trait SeqInstances extends cats.kernel.instances.SeqInstances {
 
       override def toList[A](fa: Seq[A]): List[A] = fa.toList
 
+      override def toIterable[A](fa: Seq[A]): Iterable[A] = fa
+
       override def reduceLeftOption[A](fa: Seq[A])(f: (A, A) => A): Option[A] =
         fa.reduceLeftOption(f)
 
diff --git a/core/src/main/scala/cats/instances/sortedMap.scala b/core/src/main/scala/cats/instances/sortedMap.scala
index 73a8d84374..81caffbbda 100644
--- a/core/src/main/scala/cats/instances/sortedMap.scala
+++ b/core/src/main/scala/cats/instances/sortedMap.scala
@@ -114,6 +114,8 @@ trait SortedMapInstances extends SortedMapInstances2 {
 
       override def toList[A](fa: SortedMap[K, A]): List[A] = fa.values.toList
 
+      override def toIterable[A](fa: SortedMap[K, A]): Iterable[A] = fa.values
+
       override def collectFirst[A, B](fa: SortedMap[K, A])(pf: PartialFunction[A, B]): Option[B] =
         fa.collectFirst(new PartialFunction[(K, A), B] {
           override def isDefinedAt(x: (K, A)): Boolean = pf.isDefinedAt(x._2)
diff --git a/core/src/main/scala/cats/instances/sortedSet.scala b/core/src/main/scala/cats/instances/sortedSet.scala
index 377ed5a4f8..54ed34ea07 100644
--- a/core/src/main/scala/cats/instances/sortedSet.scala
+++ b/core/src/main/scala/cats/instances/sortedSet.scala
@@ -48,6 +48,8 @@ trait SortedSetInstances extends SortedSetInstances1 {
 
       override def toList[A](fa: SortedSet[A]): List[A] = fa.toList
 
+      override def toIterable[A](fa: SortedSet[A]): Iterable[A] = fa
+
       override def reduceLeftOption[A](fa: SortedSet[A])(f: (A, A) => A): Option[A] =
         fa.reduceLeftOption(f)
 
diff --git a/core/src/main/scala/cats/instances/tuple.scala b/core/src/main/scala/cats/instances/tuple.scala
index 6e0e945222..b74d9bbb1c 100644
--- a/core/src/main/scala/cats/instances/tuple.scala
+++ b/core/src/main/scala/cats/instances/tuple.scala
@@ -98,6 +98,10 @@ sealed private[instances] trait Tuple2Instances extends Tuple2Instances1 {
 
       override def size[A](fa: (X, A)): Long = 1L
 
+      override def toList[A](fa: (X, A)): List[A] = fa._2 :: Nil
+
+      override def toIterable[A](fa: (X, A)): Iterable[A] = toList(fa)
+
       override def get[A](fa: (X, A))(idx: Long): Option[A] =
         if (idx == 0L) Some(fa._2) else None
 
diff --git a/core/src/main/scala/cats/instances/vector.scala b/core/src/main/scala/cats/instances/vector.scala
index a9e53a9a0c..90e0a313b5 100644
--- a/core/src/main/scala/cats/instances/vector.scala
+++ b/core/src/main/scala/cats/instances/vector.scala
@@ -155,6 +155,8 @@ trait VectorInstances extends cats.kernel.instances.VectorInstances {
 
       override def toList[A](fa: Vector[A]): List[A] = fa.toList
 
+      override def toIterable[A](fa: Vector[A]): Iterable[A] = fa
+
       override def reduceLeftOption[A](fa: Vector[A])(f: (A, A) => A): Option[A] =
         fa.reduceLeftOption(f)