smithy4s.capability.EncoderK.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 typeclass abstracting over the notion of encoder.
* It offers way to go from an encoder type to a function, and vice-versa.
*
* This abstraction is particularly useful when encoding unions : as we need
* to pre-compile codecs for each union member, and dispatch union instances
* to a specific codec.
*/
trait EncoderK[F[_], Result] extends Contravariant[F] {
def apply[A](fa: F[A], a: A): Result
def absorb[A](f: A => Result): F[A]
def contramap[A, B](fa: F[A])(f: B => A): F[B] =
absorb[B](b => apply[A](fa, f(b)))
}
object EncoderK {
implicit def encoderKForFunction[B]: EncoderK[* => B, B] =
new EncoderK[* => B, B] {
def apply[A](fa: A => B, a: A): B = fa(a)
def absorb[A](f: A => B): A => B = f
}
}