com.github.tonivade.purefun.instances.ProducerInstances Maven / Gradle / Ivy

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/*
 * Copyright (c) 2018-2020, Antonio Gabriel Muñoz Conejo 
 * Distributed under the terms of the MIT License
 */
package com.github.tonivade.purefun.instances;

import com.github.tonivade.purefun.Function1;
import com.github.tonivade.purefun.Kind;
import com.github.tonivade.purefun.Producer;
import com.github.tonivade.purefun.ProducerOf;
import com.github.tonivade.purefun.Producer_;
import com.github.tonivade.purefun.typeclasses.Applicative;
import com.github.tonivade.purefun.typeclasses.Comonad;
import com.github.tonivade.purefun.typeclasses.Functor;
import com.github.tonivade.purefun.typeclasses.Monad;

public interface ProducerInstances {

  static Functor functor() {
    return ProducerFunctor.INSTANCE;
  }

  static Applicative applicative() {
    return ProducerApplicative.INSTANCE;
  }

  static Monad monad() {
    return ProducerMonad.INSTANCE;
  }

  static Comonad comonad() {
    return ProducerComonad.INSTANCE;
  }
}

interface ProducerFunctor extends Functor {

  ProducerFunctor INSTANCE = new ProducerFunctor() {};

  @Override
  default  Kind map(Kind value, Function1 mapper) {
    return value.fix(ProducerOf::narrowK).map(mapper);
  }
}

interface ProducerPure extends Applicative {

  @Override
  default  Kind pure(T value) {
    return Producer.cons(value);
  }
}

interface ProducerApplicative extends ProducerPure {

  ProducerApplicative INSTANCE = new ProducerApplicative() {};

  @Override
  default  Kind ap(Kind value, 
      Kind> apply) {
    return ProducerOf.narrowK(value).flatMap(t -> ProducerOf.narrowK(apply).map(f -> f.apply(t)));
  }
}

interface ProducerMonad extends ProducerPure, Monad {

  ProducerMonad INSTANCE = new ProducerMonad() {};

  @Override
  default  Kind flatMap(Kind value, Function1> mapper) {
    return value.fix(ProducerOf::narrowK).flatMap(mapper.andThen(ProducerOf::narrowK));
  }
}

interface ProducerComonad extends ProducerFunctor, Comonad {

  ProducerComonad INSTANCE = new ProducerComonad() {};

  @Override
  default  Kind coflatMap(Kind value, Function1, ? extends B> map) {
    return Producer.cons(map.apply(value));
  }

  @Override
  default  A extract(Kind value) {
    return value.fix(ProducerOf::narrowK).get();
  }
}