Exercises for learning functional programming in JS

functional_programming_in_JS.md

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.

Second exercise - Currying

Using only currying and split make a function called "words" that returns a list of words in a string. Split function is in Ramda R.split or in lodash _.split or you can use any another function that works similar to JavaScript String split() method.

words('a b c'); // ['a', 'b', 'c']

Using only add and map functions create a function that increases every number in array.

function add(a, b) {
  return a + b;
}

Make a function to find the smallest number in an array. Use only less function and one of the listed below functions: map, filter, reduce.

function less(a, b) {
  return a < b ? a : b;
}

Third exercise - Recursion

Implement a recursive version of the flatMapDeep function. Implement a recursive version of the forEach function.

Fourth exercise - composing, currying, streams(?), etc.

Using Web Service of "MusicBrainz project" do following tasks:

• Display average length of tracks in the release and in the every single disk. Link to data.
• Display album titles list with release date. Albums can not be of a type "compilation". The list should be sorted by the release date of the album. Link to data.
• Present the results in a fancy way! The better, the more points you will get.
• Additional task: try to get any additional/interesting information from the database using as many functions as possible from lodash or Ramda.

Fifth exercise (extra credit)

Using only reduce implement functions: sum, any, max, concat. Extract the common parts of this, propose API, describe the structure of common parts.

Project assessment criteria

We will evaluate the implementation of projects as follows:

• Code is written in a function style or not? Pure, pointfree, etc.
• Quality of tests.
• Team ingenuity.