Message: 10 Date: Sun, 23 Oct 2011 21:42:20 -0400 From: Brent Yorgey Subject: Re: [Haskell-beginners] problem installing checkers To: beginners@haskell.org Message-ID: <20111024014220.GB26246@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@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@britt-fr07 ~]$ ghc-pkg check [britt@britt-fr07 ~]$