Difference between objects

diffObjs.js

import R from 'ramda'

const groupObjBy = R.curry(R.pipe(
  // Call groupBy with the object as pairs, passing only the value to the key function
  R.useWith(R.groupBy, [R.useWith(R.__, [R.last]), R.toPairs]),
  R.map(R.fromPairs)
))

const diffObjs = R.pipe(
  R.useWith(R.mergeWith(R.merge), [R.map(R.objOf("leftValue")), R.map(R.objOf("rightValue"))]),
  groupObjBy(R.cond([
    [
      R.both(R.has("leftValue"), R.has("rightValue")),
      R.pipe(R.values, R.ifElse(R.apply(R.equals),
        R.always("common"),
        R.always("difference")))
    ],
    [R.has("leftValue"), R.always("onlyOnLeft")],
    [R.has("rightValue"), R.always("onlyOnRight")],
  ])),
  R.evolve({
    common: R.map(R.prop("leftValue")),
    onlyOnLeft: R.map(R.prop("leftValue")),
    onlyOnRight: R.map(R.prop("rightValue"))
  })
);