com.github.tonivade.purefun.instances.TrampolineInstances 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.free.Trampoline;
import com.github.tonivade.purefun.free.TrampolineOf;
import com.github.tonivade.purefun.free.Trampoline_;
import com.github.tonivade.purefun.typeclasses.Applicative;
import com.github.tonivade.purefun.typeclasses.Defer;
import com.github.tonivade.purefun.typeclasses.Functor;
import com.github.tonivade.purefun.typeclasses.Monad;

public interface TrampolineInstances {

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

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

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

  static Defer defer() {
    return TrampolineDefer.INSTANCE;
  }
}

interface TrampolineFunctor extends Functor {

  TrampolineFunctor INSTANCE = new TrampolineFunctor() {};

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

interface TrampolinePure extends Applicative {

  @Override
  default  Kind pure(T value) {
    return Trampoline.done(value);
  }
}

interface TrampolineApplicative extends TrampolinePure {

  TrampolineApplicative INSTANCE = new TrampolineApplicative() {};

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

interface TrampolineMonad extends TrampolinePure, Monad {

  TrampolineMonad INSTANCE = new TrampolineMonad() {};

  @Override
  default  Kind flatMap(Kind value,
      Function1> map) {
    return TrampolineOf.narrowK(value).flatMap(map.andThen(TrampolineOf::narrowK));
  }
}

interface TrampolineDefer extends Defer {

  TrampolineDefer INSTANCE = new TrampolineDefer() {};

  @Override
  default  Kind defer(Producer> defer) {
    return Trampoline.more(() -> defer.get().fix(TrampolineOf::narrowK));
  }
}