functional-programming-learning-path/javascript/partial_application.js at master · imteekay/functional-programming-learning-path · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
/*
  Partial application is a way to turn a function that expects multiple parameters
  into one that will keep returning a new function until it receives all its arguments

  "partially apply" some of the arguments now, filling in the rest later.

  Partial application allows us to partially apply certain argument to create
  new functions out of existing ones.
*/

const calculateTotal = (amount) => {
  return (amount * 1.08) + 10;
}

const R = require('ramda');
const applyTaxOfEightPercent = R.partial(applyTax, [0.08]);

applyTaxOfEightPercent(100); // 108
applyTaxOfEightPercent(200); // 216
applyTaxOfEightPercent(190); // 205.2
applyTaxOfEightPercent(10000); // 10800