Laying out the differences (pun intended) between boolean difference & the proposed 'negate()/negative()' operation

differenceVSnegate.js

// with difference only, assuming that the details of partWithCuts are known (otherwise it cannot work)
const partWithCuts = () => {
  const block = cube()
  const cutOut = cylinder()
  const cutOut2 = cylinder()
  // not useable, information about cut is lost
  // return difference(block, cutOut, cutout2)
  return {keep: [block], remove: [cutOut, cutOut2]}
}

const main = () => {
  const somePart = cube()
  const pwc = partWithCuts()
  
  let tmpResult = somePart
  // ugh
  if('keep' in pwc){
    tmpResult = union(tmpResult, pwc.keep)
  }
  if('remove' in pwc){
    tmpResult = difference(tmpResult, pwc.remove)
  }
  
  return tmpResult
}
/////////////////////////////////////////////////////////////////////////
// with negate, works even when assuming that the details of partWithCuts are not known ! 
const partWithCuts = () => {
  const block = cube()
  const cutOut = negate(cylinder())
  const cutOut2 = negate(cylinder())
  return [union(block, cutOutn cutOut2), cutOut, cutOut2]// negativity is baked in (no jokes :)
  // this also would work, but has a slightly different meaning/ implication
  return [block, cutOut, cutOut2]
}

const main = () => {
  const somePart = cube()
  const pwc = toArray(partWithCuts())// toArray to ensure array/iterable data
  
  return union(somePart, pwc)
  // if we want to reuse the cutouts to the next , higher scope we could do:
  return [union(somePart, pwc), pwc.filter(x => isNegative(x)]
}
                                           
// with negate & nested parts
const partWithCuts = () => {
  const block = cube()
  const cutOut = negate(cylinder())
  const cutOut2 = negate(cylinder())
  return [union(block, cutOutn cutOut2), cutOut, cutOut2]// negativity is baked in (no jokes :)
  // this also would work, but has a slightly different meaning/ implication
  return [block, cutOut, cutOut2]
}

const nestedPart = () => {
  const pwc = toArray(partWithCuts())// toArray to ensure array/iterable data
  const someStuff = cube()
  return [union(somePart, pwc), pwc.filter(x => isNegative(x)] // we just return the cutouts
}

const main = () => {
  const somePart = cube()
  const nested = toArray(nestedPart())// toArray to ensure array/iterable data
  
  return union(somePart, nested)
}