Proposal #2998: Expose the internals of the network library to make it more extensible

[Johan Tibell]

Hi all,

In short, I propose that we export some of the internals of the
network library in a new module to make it easier to write portable
libraries on top of the library. I've added the full proposal, copied
from Trac, below. The motivating example is network-bytestring which
needs to marshall different socket related data types to support e.g.
`sendmsg`.

http://hackage.haskell.org/trac/ghc/ticket/2998

Discussion deadline: 2 weeks (non disruptive change)

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When creating new libraries on top of the network library it would be
convenient if the library exposed some functions that hide platform
variations so that the new libraries can be written in a portable
manner.

Take for example the currently un-exported pokeSockAddr function which
marshalls a SockAddr into a sockaddr struct. This function would be
useful when e.g. writing a binding for the sendmsg system call.
However, it's not exported so libraries are forced to define their own
version.

This is unfortunate. I propose we add a new module,
Network.Socket.Internal, to the network library, that exposes these
portable marshalling functions. It might also be a good idea to expose
some internal data representations in the same way bytestring
currently does. People who write code that uses this internal do so
knowing that there is a risk that the interface and data
representations might change.

I've written a patch that exposes some of the library's internal
functions. There are still some documentation to write and perhaps a
few more functions to expose but I think we should reach consensus on
whether this is a good idea to begin with before continuing.

Since this change isn't disruptive I propose a two week consideration deadline.

Cabal package:

http://johantibell.com/network-2.2.1.tar.gz

Haddock:

http://johantibell.com/network/doc/html/network/

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Cheers,

Johan