Leibniz formula for π using Dynamic Collections 1.2.8

gistfile1.java

package com.jnape.dynamiccollection;

import com.jnape.dynamiccollection.lambda.Function;
import com.jnape.dynamiccollection.list.DynamicList;

import static com.jnape.dynamiccollection.lambda.library.numeric.accumulator.Add.plus;
import static com.jnape.dynamiccollection.lambda.library.numeric.accumulator.Subtract.minus;
import static com.jnape.dynamiccollection.list.NumericDynamicArrayList.fromTo;

public class LeibnizSeries {

    public static void main(String[] args) {
        Number pi = convergenceAfterNTerms(1000000);
        System.out.println(pi);
    }

    private static Number convergenceAfterNTerms(int n) {
        return fromTo(0, n).map(toTerm()).inGroupsOf(2).map(toDifference()).reduce(plus());
    }

    private static Function<Number, Number> toTerm() {
        return new Function<Number, Number>() {
            @Override
            public Number apply(Number number) {
                float divisorAtIndex = number.floatValue() + number.floatValue() + 1
                return 4 / divisorAtIndex;
            }
        };
    }

    private static Function<DynamicList<Number>, Number> toDifference() {
        return new Function<DynamicList<Number>, Number>() {
            @Override
            public Number apply(DynamicList<Number> numbers) {
                return numbers.reduce(minus());
            }
        };
    }
}