Valid Writer in javascript?

Writer.js

// Based on http://adit.io/posts/2013-06-10-three-useful-monads.html

import map      from 'ramda/src/map'
import compose  from 'ramda/src/compose'
import curry    from 'ramda/src/curry'
import multiply from 'ramda/src/multiply'

const chain   = curry((fn, m) => m.chain(fn))
const read    = m => m.read()

function Writer(log, value) {
  const read  = () => ({ log: log.slice(), value })
  const map   = fn => Writer(log.slice(), fn(value))
  const of    = x => Writer([], x)

  function chain(fn) {
    const w = fn(value).read()
    // maybe think about using a Monoid for `log`?
    return Writer([].concat.call(log, w.log), w.value)
  }

  return { read, map, chain, of }
}

const addWriter       = curry((x, y) => Writer(`adding ${x} to ${y}`, x + y))
const multiplyWriter  = curry((x, y) => Writer(`multiplying ${x} by ${y}`, x * y))

const flow = compose(
  chain(multiplyWriter(25)),
  chain(addWriter(200)),
  map(multiply(10)),
  addWriter(2)
)

const readFlow = compose(read, flow)

console.log(readFlow(23))