smithy4s.capability.Zipper.scala Maven / Gradle / Ivy
/*
* Copyright 2021-2024 Disney Streaming
*
* Licensed under the Tomorrow Open Source Technology License, Version 1.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* https://disneystreaming.github.io/TOST-1.0.txt
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package smithy4s.capability
/**
* A zipper is similar in notion to `Applicative`, in that it allows for
* combining several values of `F` in non-sequential ways.
*
* The encoding here is specialised towards the traversal of sequences,
* which is something that's done heavily in this codebase.
*/
trait Zipper[F[_]] extends Covariant[F] {
def pure[A](a: A): F[A]
def zipMapAll[A](seq: IndexedSeq[F[Any]])(f: IndexedSeq[Any] => A): F[A]
def zipMap[A, B, C](fa: F[A], fb: F[B])(f: (A, B) => C): F[C] =
zipMapAll(IndexedSeq(fa, fb).asInstanceOf[IndexedSeq[F[Any]]])(seq =>
f(seq(0).asInstanceOf[A], seq(1).asInstanceOf[B])
)
override def map[A, B](fa: F[A])(f: A => B): F[B] =
zipMapAll(IndexedSeq(fa.asInstanceOf[F[Any]]))(seq =>
f(seq(0).asInstanceOf[A])
)
}
object Zipper {
def apply[F[_]](implicit ev: Zipper[F]): ev.type = ev
}