Composing Functions in Java

ComposingFunctions.java

import java.math.BigDecimal;
import java.util.function.Function;

import static java.lang.String.format;

class ComposingFunctions {

    public static void main(String[] args) {
        
        Function<BigDecimal, Integer> asInteger = a -> a.intValue();
        Function<Integer, String> describe = a -> format("Number is %s", a);

        //manual invocation of functions
        System.out.println(format("Manual fx output is %s",
                describe.apply(asInteger.apply(new BigDecimal("3.00")))));

        Function<BigDecimal, String> composedDescribe = describe.compose(asInteger);

        //invoking functions via composition
        System.out.println(format("Composed fx output is %s",
                composedDescribe.apply(new BigDecimal("3.00"))));

    }
}