Function lazyGetter

packages/effect-app/src/utils.ts:539–558

(creator: (target: T) => T2)

}

export function lazyGetter<T extends object, T2>(creator: (target: T) => T2) {
  const key = Symbol(creator.name)
  const f = (target: T): T2 => {
    let lazy = (target as unknown as Lazy)[LazySymbol]
    if (!lazy) {
      lazy = {}
      Object.defineProperty(target, LazySymbol, { enumerable: false, value: lazy })
    } else if (lazy[key]) {
      return lazy[key]
    }
    const value = creator(target)
    lazy[key] = value
    return value
  }
  Object.defineProperty(f, "name", {
    enumerable: false,
    value: `Lazy<${creator.name}>`
  })
  return f
}

export function exhaustiveMatch<T extends string>() {
  return <Out extends Record<T, (t: T) => any>>(handlers: Out) => (t: T): ReturnType<Out[keyof Out]> => handlers[t](t)