[Haskell-cafe] [ANNOUNCE] GHC 8.2.1 available

[Evan Laforge]

Thanks for the reply.  I got cabal-install from
https://github.com/haskell/cabal/ and assumed it was the latest
version... but now that I look carefully I see it has a 2.0 branch.  I
compiled it and I don't get that confusing "parse error" any more.  It
looks like a nicer error message in general too (except still missing
some spaces, specifically "After searching the rest of the dependency
tree exhaustively, these were the goals I've had most trouble
fulfilling: karya, ekgTrying configure anyway."), so that's probably
thanks to the solver improvements in 2.0.

Since it's apparently just a bug in older cabal-installs I guess I
won't bother trying to find it.

On Wed, Jul 26, 2017 at 7:01 PM, Wolfgang Jeltsch
<wolfgang-it at jeltsch.info> wrote:
> Hi!
>
> I ran into the same problem.
>
> Apparently, we need cabal-install 2.0, which has not been released yet.
> A preliminary solution is to use the development version from the 2.0
> branch. Binary packages can be found at
>
>      http://ppa.launchpad.net/hvr/ghc/ubuntu/pool/main/c/cabal-install-2.0/  ,
>
> for example. It is possible to extract the cabal-install executable from
> these packages, so that it can be installed without using some Linux
> distribution package manager.
>
> All the best,
> Wolfgang
>
> Am Mittwoch, den 26.07.2017, 18:45 -0700 schrieb Evan Laforge:
>> This seems like a silly question, but how can we install cabal-install
>> now?  The latest hackage version 1.24.0.2 has Cabal (>=1.24.2 &&
>> <1.25), but it looks like ghc Cabal is now at 2.*.
>>
>> I ran into this because if I get:
>>
>> % cabal install --only-dependencies
>> Resolving dependencies...
>> cabal: internal error when reading package index: failed to parse
>> .cabal
>> fileThe package index or index cache is probably corrupt. Running
>> cabal update
>> might fix it.
>>
>> It seems to be triggered by having 'ekg' in the deps list, since if I
>> take it out then I get some other errors about packages not liking the
>> new base, which is true.  'ekg' also doesn't like the new base, but
>> "internal error" is not the clearest way to express that :)
>>
>> It's frustrating that cabal-install still doesn't report the parse
>> error, even though the parse function returns one.  It just ignores
>> the ParseFailed case.  I was going to try fixing it and send a pull
>> request when I ran into the Cabal 2.* problem.
>>
>> On Wed, Jul 26, 2017 at 7:15 AM, Ben Gamari <ben at smart-cactus.org>
>> wrote:
>> >
>> > Wolfgang Jeltsch <wolfgang-it at jeltsch.info> writes:
>> >
>> > >
>> > > Am Samstag, den 22.07.2017, 23:03 -0400 schrieb Ben Gamari:
>> > > >
>> > > > In addition, there are a number of new features,
>> > > >
>> > > >  * A new, more type-safe type reflection mechanism
>> > > >
>> > > >  * The long-awaited Backpack module system
>> > > >
>> > > >  * Deriving strategies to disambiguate between GHC's various
>> > > > instance
>> > > >    deriving mechanisms
>> > > >
>> > > >  * Unboxed sum types, for efficient unpacked representation of
>> > > > sum
>> > > >    data types
>> > > >
>> > > >  * Compact regions, allowing better control over garbage
>> > > > collection
>> > > >    in the presence of large heaps containing many long-lived
>> > > > objects.
>> > > >
>> > > >  * Colorful messages and caret diagnostics for more legible
>> > > > errors
>> > > >
>> > > > A more thorough list of the changes in this release can be found
>> > > > in
>> > > > the release notes,
>> > > >
>> > > >   https://haskell.org/ghc/docs/8.2.1/docs/html/users_guide/8.2.1
>> > > > -notes.html
>> > > It seems that the release notes mention the new type reflection
>> > > mechanism und colorful messages only in the “Highlights” section,
>> > > not in
>> > > the “Full details” section, and that they do not mention the
>> > > Backpack
>> > > module system and unboxed sums at all.
>> > >
>> > Yes, indeed these were oversights. They are fixed in the ghc-8.2
>> > branch
>> > and I will try to push newly generated documentation shortly.
>> >
>> > Cheers,
>> >
>> > - Ben
>> >
>> > _______________________________________________
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>> > Glasgow-haskell-users at haskell.org
>> > http://mail.haskell.org/cgi-bin/mailman/listinfo/glasgow-haskell-use
>> > rs
>> >