Java 8 partial functions... see https://www.pgrs.net/2015/04/23/partial-function-application-in-java-8/?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+pgrs+%28Paul+Gross%27s+Blog%29

Example.java

@FunctionalInterface
interface TriFunction<T, U, V, R> {
    R apply(T a, U b, V c);
}
 
public class Example {
    public static int add(int x, int y) {
        return x + y;
    }
 
    public static int add3(int x, int y, int z) {
        return x + y + z;
    }
 
    public static <T, U, R> Function<U, R> partial(BiFunction<T, U, R> f, T x) {
        return (y) -> f.apply(x, y);
    }
 
    public static <T, U, V, R> Function<V, R> partial(TriFunction<T, U, V, R> f, T x, U y) {
        return (z) -> f.apply(x, y, z);
    }
 
    public static <T, U, V, R> BiFunction<U, V, R> partial(TriFunction<T, U, V, R> f, T x) {
        return (y, z) -> f.apply(x, y, z);
    }
 
    public static void main(String[] args) {
        Function adder = partial(Example::add, 5);
        System.out.println(adder.apply(1)); // 6
 
        BiFunction<Integer, Integer, Integer> minus = (x, y) -> x - y;
        Function subtractor = partial(minus, 10);
        System.out.println(subtractor.apply(4)); // 6
 
        Function adder3 = partial(Example::add3, 1, 2);
        System.out.println(adder3.apply(3)); // 6
 
        BiFunction adder3_2 = partial(Example::add3, 1);
        System.out.println(adder3_2.apply(2, 3)); // 6
    }
}