Functional Java gist solution

WeatherMunging

package org.timgroup.dojo;

import fj.Effect;
import fj.F;
import fj.F2;
import fj.data.Stream;

import static fj.data.Array.array;
import static org.timgroup.dojo.WeatherMunging.TemperatureMeasure.MAX_SPREAD;

public class WeatherMunging {
    private final Stream<String> lines;

    public WeatherMunging(Stream<String> lines) {
        this.lines = lines;
    }

    public int dayWithTheSmallestTemperatureSpread() {
        return lines.filter(startsWithADigit())
             .map(splitOnSpaces())
             .map(collectFirstThreeFieldsColumnsAsIntegers())
             .map(toTemperatureMeasure())
             .foldLeft(smallestSpread(), MAX_SPREAD).dayNumber;
    }











































    private F<String[], Stream<Integer>> collectFirstThreeFieldsColumnsAsIntegers() {
        return new F<String[], Stream<Integer>>() {

            @Override
            public Stream<Integer> f(String[] fields) {
                return array(fields).toStream().drop(1).take(3).map(blabla());
            }

            private F<String, Integer> blabla() {
                return new F<String,Integer>() {

                    @Override
                    public Integer f(String field) {
                        return Integer.valueOf(field.replaceAll("\\D", ""));
                    }};
            }};
    }

    private F2<TemperatureMeasure, TemperatureMeasure, TemperatureMeasure> smallestSpread() {
        return new F2<TemperatureMeasure, TemperatureMeasure, TemperatureMeasure>(){

            @Override
            public TemperatureMeasure f(TemperatureMeasure currentMinMeasure, TemperatureMeasure todayMeasure) {
                return (todayMeasure.tempSpread < currentMinMeasure.tempSpread) ? todayMeasure : currentMinMeasure;
            }};
    }

    private F<Stream<Integer>, TemperatureMeasure> toTemperatureMeasure() {
        return new F<Stream<Integer>, TemperatureMeasure>() {

            @Override
            public TemperatureMeasure f(Stream<Integer> tokens) {
                return new TemperatureMeasure(tokens.index(0), tokens.index(1), tokens.index(2));
            }};
    }

    private F<String, String[]> splitOnSpaces() {
        return new F<String, String[]>(){
            @Override
            public String[] f(String line) {
                return line.split("[ ]+");
            }};
    }

    private F<String, Boolean> startsWithADigit() {
        return new F<String, Boolean>() {
            @Override
            public Boolean f(String line) {
                return line.matches("\\s*?\\d.+");
            }};
    }

    public static Effect<String> print() {
        return new Effect<String>() {

            @Override
            public void e(String line) {
                System.out.println(line);
            }};
    }

    public static class TemperatureMeasure {
        static TemperatureMeasure MAX_SPREAD= new TemperatureMeasure(-1, Integer.MAX_VALUE, 0);

        private final int dayNumber;
        private final int tempSpread;

        private TemperatureMeasure(int dayNumber, int maxTemp, int minTemp) {
            this.dayNumber = dayNumber;
            this.tempSpread = maxTemp -minTemp;
        }


    }
}