BindingNotFoundError = object of CatchableError

Container = ref object
  bindings*: Table[BindingKey, proc (): RootRef {....gcsafe, raises: [].}]

proc register[T](c: Container; implementation: proc (): T {....gcsafe, raises: [].};
                 qualifier: string = "")

proc resolve[T](c: Container; qualifier: string = ""): T {.
    ...raises: [BindingNotFoundError].}