Apply a transform function to object keys, recursively

mapKeys.js

import { fromPairs, is, map, pipe, toPairs } from 'ramda'

const isObject = is(Object)

const transformKey = transform => 
  ([k, v]) => !isObject(v) ? [transform(k), v] :
    [transform(k), mapKeys(transform)(v)] 

const mapKeys = transform => 
  pipe(
    toPairs,
    map(transformKey(transform)),
    fromPairs
  )

export default mapKeys

import mapKeys from './mapKeys'
import { toUpper } from 'ramda'

const toUpperKeys = mapKeys(toUpper)

const obj = {
  one: 1,
  two: 2,
  three: {
    four: 4,
    five: {
      six: {
        seven: 7,
        eight: {
          nine: 9
        }
      }
    }
  }
}

toUpperKeys(obj)
/*
{
  ONE: 1,
  TWO: 2,
  THREE: {
    FOUR: 4,
    FIVE: { SIX: { SEVEN: 7, EIGHT: { NINE: 9 } } }
  }
}
*/