Snippet of Lambdas.java from my FizzBuzz project.

LambdasSnippet.java

public final class Lambdas {
    public static final Lambda Identity = x -> x;

    public static final Lambda True = x -> y -> x;
    public static final Lambda False = x -> y -> y;

    public static final Lambda Zero = f -> x -> x;
    public static final Lambda Succ = n -> f -> x -> f.call(n.call(f).call(x));
    public static final Lambda Pred = n -> f -> x -> n.call(g -> h -> h.call(g.call(f))).call(ignored -> x).call(u -> u);
    public static final Lambda IsZero = f -> f.call(x -> False).call(True);

    @SuppressWarnings("unused")
    public static final Lambda Y = f -> ((Lambda) (x -> f.call(x.call(x))))
                                               .call(x -> f.call(x.call(x)));
    public static final Lambda Z = f -> ((Lambda) (x -> f.call(y -> x.call(x).call(y))))
                                               .call(x -> f.call(y -> x.call(x).call(y)));

    public static final Lambda Add = x -> x.call(Succ);
    public static final Lambda Subtract = x -> y -> y.call(Pred).call(x);

    public static final Lambda IsLessOrEqual = x -> y -> IsZero.call(Subtract.call(x).call(y));

    public static final Lambda If = p -> t -> f -> p.call(t).call(f);

    ...
}