Discussion on: Ask me dumb questions about functional programming

To me, functional programming is all about composing (or combining) functions to create new functions.

A good example of this would be map and it's siblings filter and reduce.

Imperative

const values = [1, 2, 3]

let sum = 0
for (const x of values) {
  sum = sum + x
}

Functional

const values = [1, 2, 3]

const add = (x, y) => x + y
let sum = values.reduce(add)

Instead of coding all the steps to create the sum, we told reduce to use the add function.

If we were using something like Ramda, we could even do this to create a new function:

import { reduce } from 'ramda'

const add = (x, y) => x + y

// Here we are composing a new function `sum` from `reduce` and `add`.
const sum = reduce (add) (0)

const values = [1, 2, 3]
sum (values) //=> 6

To be able to compose functions like this, you need to also create pure functions, curried functions and also have immutable data. Which is why functional programming can be tricky to learn. It's not difficult to learn, it just takes time to fully understand the why.

I hope this was helpful!

Cheers!