[Haskell-beginners] problem installing checkers

[Britt Anderson]

> Message: 10
> Date: Sun, 23 Oct 2011 21:42:20 -0400
> From: Brent Yorgey <byorgey at seas.upenn.edu>
> Subject: Re: [Haskell-beginners] problem installing checkers
> To: beginners at haskell.org
> Message-ID: <20111024014220.GB26246 at seas.upenn.edu>
> Content-Type: text/plain; charset=us-ascii
>
> On Sun, Oct 23, 2011 at 06:56:57PM -0400, Britt Anderson wrote:
>> I wanted to try reactive, but cabal install fails on checkers (a
>> dependency). Here is a portion of the error message, there are other
>> overlapping instances that follow. Can someone advise me how to
>> proceed. Thank you.
>>
>> [13 of 15] Compiling Test.QuickCheck.Classes (
>> src/Test/QuickCheck/Classes.hs, dist/build/Test/QuickCheck/Classes.o )
>>
>> src/Test/QuickCheck/Classes.hs:137:38:
>>     Overlapping instances for Show (a -> b)
>>       arising from a use of `property'
>>     Matching instances:
>>       instance Show (a -> b) -- Defined in Text.Show.Functions
>>       instance Show base:System.Event.Manager.IOCallback
>>         -- Defined in base:System.Event.Manager
>
> This is very naughty of System.Event.Manager, to define IOCallback as
> a *type synonym* for a certain function type, and then declare a Show
> instance for it.  However, the instance shouldn't come into play
> unless System.Event.Manager is imported, and I don't think it is. So
> this error message seems rather odd to me.  What version of GHC do you
> have?  What is the output of 'ghc-pkg list' and 'ghc-pkg check'?
>
> -Brent
>


Here is the print out of the last part of the error message when doing
sudo cabal install reactive --global followed by the ghc-pkg list and
ghc-pkg check functions.
Thank you,

...

src/Test/QuickCheck/Classes.hs:514:37:
    Overlapping instances for Show (a -> m)
      arising from a use of `property'
    Matching instances:
      instance Show (a -> b) -- Defined in Text.Show.Functions
      instance Show base:System.Event.Manager.IOCallback
        -- Defined in base:System.Event.Manager
    (The choice depends on the instantiation of `a, m'
     To pick the first instance above, use -XIncoherentInstances
     when compiling the other instance declarations)
    In the expression: property foldMapP
    In the expression: ("foldMap", property foldMapP)
    In the expression:
      [("fmap", property fmapP), ("foldMap", property foldMapP)]
cabal: Error: some packages failed to install:
category-extras-0.53.5 failed during the building phase. The exception was:
ExitFailure 1
checkers-0.2.8 failed during the building phase. The exception was:
ExitFailure 1
reactive-0.11.5 depends on checkers-0.2.8 which failed to install.
[britt at britt-fr07 ~]$ ghc-pkg list
/usr/lib/ghc-7.0.3/package.conf.d
   Boolean-0.0.1
   Cabal-1.10.1.0
   GLFW-0.4.2
   GLURaw-1.1.0.0
   HTTP-4000.1.1
   HUnit-1.2.2.3
   MemoTrie-0.4.10
   MissingH-1.1.0.3
   ObjectName-1.0.0.0
   OpenGL-2.4.0.1
   OpenGLRaw-1.1.0.1
   QuickCheck-2.4.1.1
   StateVar-1.0.0.0
   Stream-0.4.2
   Tensor-1.0.0.1
   TypeCompose-0.8.3
   X11-1.5.0.0
   array-0.3.0.2
   base-4.3.1.0
   base64-bytestring-0.1.0.3
   bin-package-db-0.0.0.0
   binary-0.5.0.2
   bytestring-0.9.1.10
   citeproc-hs-0.3.2
   containers-0.4.0.0
   deepseq-1.1.0.2
   digest-0.0.0.9
   directory-1.1.0.0
   dlist-0.5
   extensible-exceptions-0.1.1.2
   ffi-1.0
   filepath-1.2.0.0
   ghc-7.0.3
   ghc-binary-0.5.0.2
   ghc-prim-0.2.0.0
   haskell2010-1.0.0.0
   haskell98-1.1.0.1
   hpc-0.5.0.6
   hs-bibutils-4.12
   hslogger-1.1.5
   integer-gmp-0.2.0.3
   json-0.4.4
   lazysmallcheck-0.5
   mtl-2.0.1.0
   network-2.3.0.5
   old-locale-1.0.0.2
   old-time-1.0.0.6
   pandoc-1.8.2.1
   pandoc-types-1.8.2
   parsec-3.1.1
   pretty-1.0.1.2
   process-1.0.1.5
   random-1.0.0.3
   regex-base-0.93.2
   regex-compat-0.95.1
   regex-posix-0.95.1
   rts-1.0
   syb-0.3
   tagsoup-0.12.2
   template-haskell-2.5.0.0
   texmath-0.5.0.1
   text-0.11.1.5
   time-1.2.0.3
   transformers-0.2.2.0
   unamb-0.2.4
   unix-2.4.2.0
   utf8-string-0.3.6
   vector-space-0.7.3
   xhtml-3000.2.0.1
   xml-1.3.9
   zip-archive-0.1.1.7
   zlib-0.5.3.1
[britt at britt-fr07 ~]$ ghc-pkg check
[britt at britt-fr07 ~]$