Proposal for removing transformers dependency

[Boespflug, Mathieu]

On 22 January 2015 at 09:34, Joachim Breitner <mail at joachim-breitner.de> wrote:
> Hi,
>
> Am Donnerstag, den 22.01.2015, 08:37 +0100 schrieb Herbert Valerio
> Riedel:
>> One thing to keep in mind though is that then 'haskeline' (which is
>> needed by GHCi) still remains a consumer of 'transformers', so we'd
>> still have to bundle a 'transformers' package version with GHC even if
>> `ghc` doesn't depend on it anymore. Somewhat related, the `ghc` ->
>> `Cabal` dependency was broken up in GHC 7.10 but we'll still bundle
>> `Cabal` with GHC 7.10.
>
> although there has been talk about only shipping the .so file with a
> clash-free name or path... was this not done simply because noone
> bothered enough to actually do it, or was there a bigger problem?

There was an email thread about this very problem started by Michael
Snoyman last month. As noted later in that thread,

https://www.haskell.org/pipermail/ghc-devs/2014-December/007826.html

the packages mentioned above and others were added to the ghc-pkg
database in order to address
 https://ghc.haskell.org/trac/ghc/ticket/8919, hence making the
problem worse. It sounds to me like Alexander's patch, plus the
solution alluded by Joachim above for "invisible" packages that don't
clash with ones registered in the ghc-pkg db, would allow us to avoid
having any of the following packages leaking into all sandboxes for
all users of GHC 7.10 and following:

* haskeline
* transformers
* xhtml
* terminfo

Perhaps others. That would be a big win.

Here's a more ambitious change: if we could make installation of the
ghc library itself optional, then we could avoid forcing the
installation of a whole swathe of other packages into the global db,
including transformers.

Best,

Mathieu