[Haskell-cafe] Strange discrepancy between Emacs interpreter and command-line on windows

Arnaud Bailly arnaud.oqube at gmail.com
Thu Jun 10 00:15:32 EDT 2010

Yes, I have two versions installed , and Here is the
output of ghc-pkg -l:

d:/Program Files/Haskell Platform/2009.2.0.2\package.conf:
    Cabal-, GLUT-, HSlim-0.1, HTTP-4000.0.6,
    HUnit-, OpenGL-, QuickCheck-,
    QuickCheck-, Win32-, array-, base-,
    base-, bytestring-, bytestring-,
    cgi-3001.1.7.1, containers-, directory-,
    (dph-base-0.3), (dph-par-0.3), (dph-prim-interface-0.3),
    (dph-prim-par-0.3), (dph-prim-seq-0.3), (dph-seq-0.3),
    extensible-exceptions-, fgl-, filepath-,
    (ghc-6.10.4), ghc-prim-, haddock-2.4.2, haskell-src-,
    haskell98-, hpc-, html-, integer-,
    mtl-, network-, old-locale-, old-time-,
    packedstring-, parallel-, parsec-,
    pretty-, process-, random-,
    regex-base-, regex-compat-, regex-posix-,
    rts-1.0, stm-, syb-, template-haskell-,
    time-, utf8-string-0.3.6, xhtml-3000.2.0.1, zlib-

However, I tried to force the version I use to be and it does
not work as ghc itself seems to require, as pointed out by
Ivan. I did not try to remove one or the other however.


On Thu, Jun 10, 2010 at 12:13 AM, Ivan Lazar Miljenovic
<ivan.miljenovic at gmail.com> wrote:
> Don Stewart <dons at galois.com> writes:
>> arnaud.oqube:
>>> Hello,
>>> I have a strange issue which sprang today out of nowhere. When I load
>>> a certain file using bytestring package in Ghci using emacs, I got the
>>> following error:
>>> Couldn't match expected type `Data.ByteString.Internal.ByteString'
>>>            against inferred type
>>> `bytestring-'
>>>     In the second argument of `hPutStrLn', namely `(fromString msgs)'
>>>     In a stmt of a 'do' expression: hPutStrLn cnx (fromString msgs)
>>> The same file compiles fine on the command-line. I have a single
>>> installation of haskell platform, using ghc 6.10.4, on windows XP.
>> Looks like you might have two versions of bytestring installed (ghc-pkg
>> list bytestring) and are attempting to combine them. The diamond
>> dependency problem.
>>     * delete the old version (ghc-pkg unregister)
> Isn't the old version likely to be the one that comes with GHC and hence
> shouldn't be touched?
> --
> Ivan Lazar Miljenovic
> Ivan.Miljenovic at gmail.com
> IvanMiljenovic.wordpress.com

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