Method constructor

src/client/sandbox.mjs:439–443

(mapping)

class Cached {
  constructor(mapping) {
    this.mapping = mapping
    this.work = Object.create(null)
    this.done = Object.create(null)
  }

  compute(value) {
    return this.work[value] || (this.work[value] = this.mapping(value).then(result => this.done[value] = result))