[Haskell-cafe] problems installing latest parsec

[Michael Litchard]

thanks, it seems to be fine now.

On Tue, Nov 2, 2010 at 5:04 PM, Daniel Fischer <daniel.is.fischer at web.de> wrote:
> On Wednesday 03 November 2010 00:46:13, Michael Litchard wrote:
>> Here's what cabal says I have installed
>>
>>
>> * parsec
>>     Synopsis: Monadic parser combinators
>>     Latest version available: 3.1.0
>>     Latest version installed: 2.1.0.1
>>     Homepage: http://www.cs.uu.nl/~daan/parsec.html
>>     License:  BSD3
>>
>>
>> but here is what happens when I try to upgrade
>>
>> cabal upgrade parsec
>> Resolving dependencies...
>> No packages to be installed. All the requested packages are already
>> installed. If you want to reinstall anyway then use the --reinstall
>> flag.
>> mlitchard at kether:~/projects/perf/autoperf/session_creator$
>>
>> Any clues as to what I can try next to fix things would be appreciated.
>
> $ cabal install parsec-3.1.0
>
> There's a preferred version constraint on parsec, so by default cabal
> installs parsec-2 rather than parsec-3, you have to tell it explicitly to
> install parsec-3. It might be necessary to tell cabal to use parsec-3 also
> when installing other packages that depend on parsec,
>
> $ cabal install --constraint="parsec == 3.1.0" whatever
>
> should do the trick then (if it doesn't use the --preference flag instead
> of --constraint).
>