Currying in Java 7

Functio.java

public final class Functio {
    abstract static class N1<T, U> {
        abstract U apply(T t);
    }

    abstract static class N2<T, U, V> extends N1<T, N1<U,V>> {
        abstract V apply(T t, U u);

        @Override
        N1<U, V> apply(final T t) {
            return new N1<U, V>() {
                @Override
                V apply(U u) {
                    return N2.this.apply(t, u);
                }
            };
        }
    }

    abstract static class N3<T, U, V, Y> extends N1<T, N2<U,V, Y>> {
        abstract Y apply(T t, U u, V v);

        @Override
        N2<U, V, Y> apply(final T t) {
            return new N2<U, V, Y>() {
                @Override
                Y apply(U u, V v) {
                    return N3.this.apply(t, u, v);
                }
            };
        }
    }

    public static void main(String[] args) {
        Functio.N3<Boolean, Integer, Float, String> function = new Functio.N3<Boolean, Integer, Float, String>() {
            @Override
            String apply(Boolean b, Integer i, Float f) {
                return String.format("%s-%d-%s", b, i, f);
            }
        };

        System.out.println(function.apply(true, 4, 7.5f));
        System.out.println(function.apply(true).apply(4, 7.5f));
        System.out.println(function.apply(true).apply(4).apply(7.5f));
    }
}