curry.js

// Auto Curry "Magic Spell", by Eric Elliott
// https://medium.com/javascript-scene/a-functional-programmers-introduction-to-javascript-composing-software-d670d14ede30
const curry = (
  f, arr = []
) => (...args) => (
  a => a.length === f.length ?
    f(...a) :
    curry(f, a)
)([...arr, ...args]);