Changes to the type checker with respect to UndecidableInstances

2014-12-28 Thread Mitsutoshi Aoe
Hi,

I found a difference between GHC 7.6.3 and 7.8.3 with respect to 
UndecidableInstances.

https://gist.github.com/maoe/57a4346eb36aee159916 
https://gist.github.com/maoe/57a4346eb36aee159916

7.6.3 requires UndecidableInstances to compile this snippet whereas 7.8.3 
doesn't. What has changed in the type checker?

Mitsutoshi

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Re: GHC 7.4.2 on Ubuntu Trusty

2014-12-28 Thread Yitzchak Gale
Resurrecting this thread:

My impression was that Edward's suggestion was a simple and
obvious solution to the problem of previous GHC versions quickly
becoming orphaned and unbuildable. But Austin thought that this
thread was stuck.

Would Edward's suggestion be difficult to implement for any
reason? Specifically, right now would be the time to do it, and
it would mean:

1. Create a 7.8.5 branch.
2. Tweak the stage 1 Haskell sources to build with 7.10 and tag
3. Create only a source tarball and upload it to the download
site

Thanks,
Yitz


On Wed, Oct 29, 2014 at 12:10 AM, Edward Z. Yang wrote:
 Excerpts from Yitzchak Gale's message of 2014-10-28 13:58:08 -0700:
 How about this: Currently, every GHC source distribution
 requires no later than its own version of GHC for bootstrapping.
 Going backwards, that chops up the sequence of GHC versions
 into tiny incompatible pieces - there is no way to start with a
 working GHC and work backwards to an older version by compiling
 successively older GHC sources.

 If instead each GHC could be compiled using at least one
 subsequent version, the chain would not be broken. I.e.,
 always provide a compatibility flag or some other reasonably
 simple mechanism that would enable the current GHC to
 compile the source code of at least the last previous released
 version.

 Here is an alternate proposal: when we make a new major version release,
 we should also make a minor version release of the previous series, which
 is prepped so that it can compile from the new major version.  If it
 is the case that one version of the compiler can compile any other
 version in the same series, this would be sufficient to go backwards.

 Concretely, the action plan is very simple too: take 7.6 and apply as
 many patches as is necessary to make it compile from 7.8, and cut
 a release with those patches.

 Edward
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Re: ANNOUNCE: GHC 7.10.1 Release Candidate 1

2014-12-28 Thread cg

*From:* Austin Seipp mailto:aus...@well-typed.com
*Sent:* ‎Tuesday‎, ‎December‎ ‎23‎, ‎2014 ‎15‎:‎36
*To:* ghc-d...@haskell.org mailto:ghc-d...@haskell.org,
glasgow-haskell-users@haskell.org mailto:glasgow-haskell-users@haskell.org

We are pleased to announce the first release candidate for GHC 7.10.1:

 https://downloads.haskell.org/~ghc/7.10.1-rc1/



Besides downloading a tarball, can I checkout it using git?

I tried using sync-all as described on wiki [1] to checkout it:

./sync-all checkout ghc-7.10

but it seems it doesn't work, there are error message like:
error: pathspec 'ghc-7.10' did not match any file(s) known to git.

[1] https://ghc.haskell.org/trac/ghc/wiki/WorkingConventions/Releases



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