function sequence(startCount, newCount) {

  var currentCount = startCount;

  return function counter() {

      currentCount += newCount;

      return currentCount;

  };

}

​

function take(gen, x) {

  var mas = [];

  for (var i = 0; i < x; i++) {

    mas.push(gen());

  }

  return mas;

}

​

function square(number) {

  return number * number;

}

​

var counter = sequence(1, 3);

​

var gen = take(counter, 5);

​

function fmap(square, counter) {

  return function () {

    return square(counter());

  };

}

​

var squareCounter = fmap(square, counter);

​

function map(square, array) {

  var arrayCopy = array;

  for (var i = 0; i < arrayCopy.length; i++) {

    arrayCopy[i] = square(arrayCopy[i]);

  }

  return arrayCopy;

}

​

var array = [1, 2, 3, 4];

​

console.log(map(square, array));

​

console.log(array);

​

​