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function* fromTo(start,end){
    for(let i = start ; i <= end ; i++) {
	yield i;
    }
}

const range = fromTo(1,3);
console.log(range.next().value);
console.log(range.next().value);
console.log(range.next().value);

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function daysBetween(date1: string, date2: string) {
  let from = new Date(date1);
  let to = new Date(date2);
  return Math.floor((to-from)/86400000);
}

console.log(daysBetween('Jan 1, 2024', 'Jan 29, 2024'));
console.log(daysBetween('Feb 29, 2020', 'Oct 31, 2023'));

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type Direction = "Vertical" | "Horizontal";

const flipArray = (array: number[][], direction: Direction): number[][] => {
  if (direction == "Vertical") {
    return array.slice().reverse();
  } else {
    return array.map((row) => [...row].reverse());
  }
};

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function combinations(arr) {
  const result = [];

  function backtrack(start, current) {
    result.push([...current]);

    for (let i = start; i < arr.length; i++) {
      current.push(arr[i]);

      backtrack(i + 1, current);

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About

I came up with these exercises for someone learning to code. But I thought more people might want to do them.

I like functional programming, so the exercises asks you to make functions that are common in functional programming. If you have learned a language, but want to learn more about functional programming, these exercises are for you.

The exercises were originally meant for Python, but doing them in JavaScript, Ruby or any Lisp (Scheme, Clojure, …) should work just as well. It should also be possible to do them in Java and C#, but it will probably not be as easy.

Most of the functions you are asked to create already exist in functional languages, or libraries for most languages. But it can be educational to implement them yourself.

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const returnGiftWindow = (acceptDate: string): Date => {
  const res = new Date();
  const dt = new Date(acceptDate);
  const month = dt.getMonth();

  if(month === 11) {
    res.setDate(dt.getDate()+90);
  }
  else {
    res.setDate(dt.getDate()+30);

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const isBitonic = (arr: number[]):boolean => {

  let left = 0;
  let right = 0;
  for(let i=0;i<arr.length-1;i++){
    left = arr[i];
    right = arr[i+1];
    if(right<left){
      console.log(left);
      return true;

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Exercises for learning functional programming in JS

During implementation you can use libraries like ramda, lodash, underscore, etc. For each exercise you have to write tests.

Link to presentation: Functional programming in Javascript

First exercise - Reduce

Implement forEach, map, filter, reduceRight and some using only reduce.

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Apple does not automatically reloads the ssh-key service after reloading.

To enable the ssh-service to load automatically after reloding into macos:

ssh-key --apple-use-keychain
ssh-key --apple-load-keychain