[Haskell-beginners] cabal install error: (Illegal instance declaration for `StrictByteString String')

21 Jan 2013


      Hi, please,....I'm trying to install one package 
(neo4j-haskell-http-client) and below is the error I'm getting. Pls. any 
ideas how can I fix that?


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1 of 1] Compiling Data.ByteString.Class ( Data/ByteString/Class.hs, 
dist/build/Data/ByteString/Class.o )

Data/ByteString/Class.hs:39:10:
     Illegal instance declaration for `StrictByteString String'
       (All instance types must be of the form (T a1 ... an)
        where a1 ... an are *distinct type variables*,
        and each type variable appears at most once in the instance head.
        Use -XFlexibleInstances if you want to disable this.)
     In the instance declaration for `StrictByteString String'

Data/ByteString/Class.hs:55:10:
     Illegal instance declaration for `LazyByteString String'
       (All instance types must be of the form (T a1 ... an)
        where a1 ... an are *distinct type variables*,
        and each type variable appears at most once in the instance head.
        Use -XFlexibleInstances if you want to disable this.)
     In the instance declaration for `LazyByteString String'
Updating documentation index /Users/miro/Library/Haskell/doc/index.html
cabal: Error: some packages failed to install:
bytestring-class-0.0.0 failed during the building phase. The exception was:
ExitFailure 1
neo4j-haskell-0.4.1 depends on bytestring-class-0.0.0 which failed to 
install.

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cheers,
m.