Splitting Network.URI from the network package

[Edward Z. Yang]

Hello Michael,

I'd like to chime in that with module reexports (a new feature landing
in GHC 7.10, see https://ghc.haskell.org/trac/ghc/wiki/ModuleReexports),
network-uri can safely reexport the Network.URI module defined in old
versions of network (if both packages are included, GHC won't consider
the import ambiguous.)

If you wanted to do things completely without breaking BC, this would
suggest making a new package network-without-uri (but obviously a better
name), and users who don't use Network.URI can switch their
build-depends against that. network also defines Network.URI, but now it
reexports modules from network-without-uri.

Cheers,
Edward

Excerpts from Michael Snoyman's message of 2014-08-01 12:31:13 +0100:
> This was brought up last year[1], and I'd like to bring it up again, based
> on a recent issue I was working through with a user[2]. I realize that this
> is a breaking change, but:
> 
> 1. It's a minor breaking change: you simply need to add an extra package to
> your build-depends.
> 2. The problems caused by having a parsec dependency in network can be
> severe, especially for new users (I'll describe the details after the
> proposal).
> 
> Concretely, I believe we should do the following:
> 
> 1. Create a new package, network-uri, version 2.5.0.0, which exposes no
> modules and has an upper bound `network < 2.6.
> 2. Create a second release of network-uri, version 3.0.0.0, which provides
> the Network.URI module verbatim as provided by the network package today,
> and has a lower bound `network >= 3.0`.
> 3. Release network version 3.0.0.0, with no changes from the currently
> released version, except that (a) no Network.URI module is provided, and
> (b) there is no parsec dependency.
> 
> I don't remember how the discussion went last time, but I seem to remember
> general consensus. I'd like to set a discussion period of two weeks (August
> 15).
> 
> ## Motivation
> 
> To give a concrete example of why this problem is severe, consider the
> following data:
> 
> * The network package is a pain to install on Windows for most users
> (especially new users), since it requires msys.
> * Most Windows users therefore install the Haskell Platform, avoiding the
> msys dependency.
> * The current release of HP installs text version 0.11.3.1. text is a
> dependency of parsec, and parsec is a dependency of network. Therefore, you
> can't build against a new version of text *and* use the network package
> without recompiling network, which as I mentioned is difficult.
> * A number of popular packages depend on newer versions of text. For
> example, since 0.8.0.0, aeson requires text version 1.1.0.0 or later. as
> does attoparsec since version 0.12.0.0.
> 
> [1] http://www.haskell.org/pipermail/libraries/2013-January/019234.html
> [2] https://groups.google.com/d/msg/yesodweb/auk2vByXgO8/lUZ9oanKyMwJ