err.log

Error:
registry.pony:7:30: this parameter must be sendable (iso, val or tag)
  be fetch(key: String, cb: ({tag (T)})) =>
                             ^
Error:
registry.pony:10:18: this parameter must be sendable (iso, val or tag)
  be access(cb: ({tag (Map[String, T tag])})) =>
                 ^
Error:
registry.pony:13:30: this parameter must be sendable (iso, val or tag)
  be put(key: String, value: T tag) =>
                             ^
Error:
registry.pony:16:33: this parameter must be sendable (iso, val or tag)
  be delete(key: String, value: T tag) =>
                                ^
Makefile:2: recipe for target 'build' failed
make: *** [build] Error 1

registry.pony

use "collections"
use "promises"

actor Registry[T]
  embed _registry: Map[String, T tag] = _registry.create()

  be fetch(key: String, cb: ({tag (T)})) =>
    cb(try _registry(key) end)

  be access(cb: ({tag (Map[String, T tag])})) =>
    cb(_registry)

  be put(key: String, value: T tag) =>
    _registry(key) = value

  be delete(key: String, value: T tag) =>
    try
      if _registry(key)? is value then
        _registry.remove(key)?
      end
    end
  
  be _fetch[A: T tag](key: String, promise: Promise[A]) =>
    try
      promise(_registry(key)? as A)
    else
      promise.reject()
    end

  fun tag apply[A: T tag = T tag](key: String): Promise[A] =>
    let promise = Promise[A]
    _fetch[A](key, promise)
    promise