ralphschuler

class BetterMap<k, v> extends Map<k, v> {
  update(key:k, updater: (v:v, k:k) => v, notset:v = undefined) {
    if(this.has(key)) this.set(key, updater(this.get(key), key))
    else this.set(key, notset)
  }

  filter(predicate: (v:v, k:k) => boolean) {
    const newMap = new BetterMap<k, v>()
    const entries = Array.from(this.entries())
    for(const [key, value] of entries) {