java 8, inspired by https://speakerdeck.com/raganwald/javascript-combinators

Combinators.java

import java.util.List;
import java.util.function.BiFunction;
import java.util.function.Function;

import static java.util.Arrays.asList;

public class Combinators {

    public static <A, B, R> BiFunction<B, A, R> flip(BiFunction<A, B, R> fn) {
        return (a, b) -> fn.apply(b, a);
    }

    public static String arrow(String a, String b) {
        return a + " -> " + b;
    }

    public static <A, B, R> Function<A, Function<B, R>> curry(BiFunction<A, B, R> fn) {
        return (a) -> (b) -> fn.apply(a, b);
    }

    public static <A, B, R>  BiFunction<A, B, R> uncurry(Function<A, Function<B, R>> fn) {
        return (a, b) -> fn.apply(a).apply(b);
    }

    public static <T, R> List<R> map(List<T> mappable, Function<T, R> fn) {
        return (List<R>) asList(mappable.stream().map(fn).toArray());
    }

    public static <T, R> Function<List<T>, List<R>> mapWith(Function<T, R> mapper) {
        BiFunction<Function<T, R>, List<T>, List<R>> flipped = flip(Combinators::map);
        return curry(flipped).apply(mapper);
    }

    public static  Integer times2(Integer i) {
        return i * 2;
    }



    public static void main(String[] args) {

        System.out.println(flip(Combinators::arrow).apply("x", "y"));

        Function<String, Function<String, String>> curriedArrow = curry(Combinators::arrow);
        System.out.println(curriedArrow.apply("finger").apply("moon"));

        Function<String, String> pointer = curry(Combinators::arrow).apply("finger");
        System.out.println(pointer.apply("moon"));

        Function<MyTestSubject, String> getter =  MyTestSubject::getName;

        System.out.println(map(asList(1, 2, 3), Combinators::times2));

        Function<List<Integer>, List<Integer>> doubleAll = mapWith(Combinators::times2);
        System.out.println(doubleAll.apply(asList(1, 2, 3)));

        Function<List<MyTestSubject>, List<String>> names = mapWith(MyTestSubject::getName);
        System.out.println(names.apply(asList(new MyTestSubject("jef"), new MyTestSubject("marie"))));
    }

    private static class MyTestSubject {
        private String name;

        private MyTestSubject(String name) {
            this.name = name;
        }

        public String getName() {
            return name;
        }
    }
}