moy-fp/src/List/adjust.js

A functional programming library.

import curry from '../Function/curry'

/**
 * Number -> (a -> a) -> [a] -> [a]
 */
const adjust = curry(
  (n, fn, array) => {
    const list = [...array],
          index = n < 0 ? n + array.length : n
    list[index] = fn(list[index])
    return list
  }
)

export default adjust