qualified imports, PVP and so on (Was: add new Data.Bits.Bits(bitZero) method)

Michael Snoyman michael at snoyman.com
Thu Feb 27 08:12:56 UTC 2014

On Thu, Feb 27, 2014 at 10:05 AM, Carter Schonwald <
carter.schonwald at gmail.com> wrote:

> i have no clue, i'm just there dealing with the fallout of a confused new
> person who is convinced that cabal just doesn't work. and no fallout
> shelters in sight so I have to provide quick solutions that work(tm) to
> prevent frustration radiation poisoning.
> why not just put all the modules in the same package?  :)
> I jest, BUT i have a real point in saying that.
> why should i have to use a wrapper package which pins all the constraints?
That's a great question. It seems to be the question no one's able to
answer, myself included. As I keep saying, Yesod went through years of PVP
compliance, and users were constantly having build problems. It may have
been the cabal-install dependency solver prior to 0.14, and now that
problem is resolved. I'm not sure. I know that the new dependency solver
used Yesod as a stress test case.

Releasing yesod-platform was pragmatic on two fronts:

1. It guaranteed a sane build plan when cabal (for whatever reason)
couldn't determine one.
2. It prevents users from getting a completely untested set of packages,
hopefully insulating them from some of the turbulence of Hackage.

I think you need to dial back your assumptions here. Your initial email
made it sound like I'd broken the Yesod stack single-handedly a bunch of
times recently. That worries me. If that actually happened, please explain
how it happened. If users are getting build errors when they don't use
yesod-platform, well, that's something we've known about in the Yesod
community for a long time. The PVP didn't solve it, yesod-platform is a
hack which fixes most of the end-user issue, and I'd love to get to a real

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