phat-arrows.js

function getAdder(a) {
  return function(b) {
    return a + b;
  };
}

// Another way to write the same is this:
// const getAdder = a => b => a + b;

const addOne = getAdder(1);
addOne(2) // 3
addOne(5) // 6

const addTen = getAdder(10);
addTen(2) // 12
addTen(5) // 15

// more:

function getErrorFormatter(prefix, suffix) {
  return function(error) {
    return `${prefix}${error.message}${suffix}`;
  };
}

// Another way to write the same is this:
// const getErrorFormatter = (prefix, suffix) => error => `${prefix}${error.message}${suffix}`;

const fooReporter = getErrorFormatter('foo <', '>');
fooReporter(new Error('what')) // foo <what>

const barReporter = getErrorFormatter('bar {', '}');
barReporter(new Error('yo')) // bar {yo}