Err package:zeromq4-haskell

ZMQ_POLLERR
We use our own functions for throwing exceptions in order to get the actual error message via zmq_strerror. 0MQ defines additional error numbers besides those defined by the operating system, so zmq_strerror should be used in preference to strerror which is used by the standard throw* functions in Error. Warning: This is an internal module and subject to change without notice.
Error number value.
ZMQError encapsulates information about errors, which occur when using the native 0MQ API, such as error number and message.