Exception always raised even with safe shutdown?

[centromere]

For sendClose:

This exception is when you can finally consider the connection closed.

If I am closing the connection properly, why should an exception ever be raised? Shouldn't exceptions only be raised for exceptional circumstances?

[jaspervdj]

I think this is the best way to have a "uniform" way of exiting out of calls like receive. Additionally, it works very well functions like bracket from Control.Exception.

The alternative would be to have receive return the close message, but that:

1. Is a breaking change (which is hard to argue for)
2. Breaks the idea that the library takes care of "control messages" (open, close, ping, continue...)