Network.Socket.recv throws IOException on reading 0 bytes

[tibbe]

Initially reported here: http://hackage.haskell.org/trac/ghc/ticket/3071

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My man pages has the following to say about the return value of recv:

These calls return the number of bytes received, or -1 if an error occurred.

For TCP sockets, the return value 0 means the peer has closed its half side of the connection.

This means that it's absolutely fine to read 0 bytes when using e.g. UDP socket.

However, the Network.Socket.recv function always throws an exception upon reading 0 bytes regardless of the protocol family.