[Haskell-cafe] Package conflicts using cabal-dev

[Arnaud Bailly]

Hello,
I am running into a strange issue that reminds me of Java's classloader
black magic havoc :-)

My code compiles fine using cabal-dev install, but when I try to compile an
individual file with ghc, I got the following error:

$ ghc  -package-conf cabal-dev/packages-7.4.1.conf YakGraph.hs
[1 of 1] Compiling YakGraph ( YakGraph.hs, YakGraph.o )

YakGraph.hs:13:30:
Couldn't match expected type `Data.Text.Lazy.Internal.Text'
with actual type
`text-0.11.2.0:Data.Text.Lazy.Internal.Text'
In the first argument of `unpack', namely `s'
In the expression: unpack s
In an equation for `fromGraphId': fromGraphId (Str s) = unpack s

YakGraph.hs:24:57:
Couldn't match expected type `Data.Text.Lazy.Internal.Text'
with actual type
`text-0.11.2.0:Data.Text.Lazy.Internal.Text'
In the first argument of `unpack', namely `name'
In the expression: unpack name
In a case alternative: (Just (Str name)) : _ - unpack name

The code leading to this error is here: https://gist.github.com/4677191

Any insights on this would be appreciated.

Arnaud
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Re: [Haskell-cafe] Package conflicts using cabal-dev

[Daniel Fischer]

On Wednesday 30 January 2013, 22:29:23, Arnaud Bailly wrote:

YakGraph.hs:13:30:
Couldn't match expected type `Data.Text.Lazy.Internal.Text'
with actual type `text-0.11.2.0:Data.Text.Lazy.Internal.Text'

one package (at least) you use - probably graphviz - was compiled with a 
version of `text` that is not the newest you have installed.

GHC selects the newest installed version of a package by default, cabal and 
cabal-dev select the version that the other used packages require.

Add a -package text-0.11.2.0 flag to the command line.



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