Re: propagating inputs in ghc-* packages

[Ricardo Wurmus <rekado@elephly.net>]

Eric Bavier <ericbavier@openmailbox.org> writes:

> Hello Ricardo,
>
> On 2016-09-30 04:24, Ricardo Wurmus wrote:
>> Hi Guix,
>> 
>> I’m in the middle of upgrading our Haskell packages.  (Actually, I’m
>> just yak shaving.  I need “pandoc-citeproc” for “r-knitr”…)
>> 
>> I noticed that upgrading Haskell packages is a pain in the neck because
>> of propagated inputs.  It seems that not all packages have fully
>> declared dependencies and just work accidentally because of propagated
>> inputs of a related package.  This also makes upgrades more difficult
>> because I can get substitutes from Hydra that depend on older versions
>> of some Haskell packages.
>> 
>> It looks like Haskell binaries actually embed references to other
>> Haskell packages, so I’m not sure we actually need to propagate 
>> anything
>> at all.  Could someone please confirm this?
>
> Commit e17d513381296b (from almost a year ago!) was intended to allow us 
> to remove propagated inputs from our ghc-* packages.  But I didn't 
> follow-up at the time, for reasons I forget now, in actually 
> un-propagating those inputs.  So if you want to try to do that, it might 
> just work.

Thank you!  That’s excellent.

Commit 2d47cee25b8bb31d22e6803f1cb3e1679641e14a removes all propagation
from haskell.scm.  I rebuilt all packages and tested that things still
work using “ghc-pandoc” both as an executable and as a library.

~~ Ricardo