gistfile1.java

package com.tinkerpop.gremlin;

import java.util.function.Function;

/**
 * @author Marko A. Rodriguez (http://markorodriguez.com)
 */
public class Monad<S, E> {

    private final Monad<?, S> start;
    private final S value;
    private final Function<S, E> function;

    public Monad(Monad<?, S> start, Function<S, E> function) {
        this.start = start;
        this.value = null;
        this.function = function;
    }

    public Monad(S value, Function<S, E> function) {
        this.start = null;
        this.value = value;
        this.function = function;
    }

    public <T> Monad<E, T> map(Function<E, T> function) {
        return new Monad<>(this, function);
    }

    public E get() {
        return function.apply((this.value == null) ? this.start.get() : this.value);
    }
}





///////////////////////////////////////////////


public class MonadTest extends TestCase {

    public void testMonad() {

        System.out.println(
                new Monad<String, Integer>("marko", String::length)
                        .map(x -> x.toString() + "1")
                        .map(x -> x.length())
                        .map(x -> x.floatValue()).get());

    }
}

// 2.0