Function composition

Function1_composition.java

public abstract class Function1<R, T1> {
    /* ... previous method definitions ... */

    public <R2> Function1<R2, T1> compose(final Function1<R2, R> f) {
        return new Function1<R2, T1>() {
            @Override
            public R2 evaluate(final Function1<R2, T1> self, final T1 i1) {
                return f.evaluate(f, Function1.this.evaluate(Function1.this, i1));
            }
        };
    }
}