Re: [Haskell-cafe] ByteString in patterns

11 Mar 2009

      manlio_perillo:
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Don Stewart ha scritto:
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manlio_perillo:
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Don Stewart ha scritto:
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[...]
    {-# LANGUAGE OverloadedStrings #-}
import qualified Data.ByteString.Char8 as C
isMatch :: C.ByteString -> Bool
    isMatch "match" = True
    isMatch _       = False
main = print . map isMatch . C.lines =<< C.getContents
What is the reason why instance declarations for IsString class are 
not  defined for available ByteStrings?
I need to define it by myself.
They're exported from Data.ByteString.Char8
Then there is something I'm missing.
Your code does not compile.
Sure it does:

    $ ghci A.hs  
    GHCi, version 6.10.1: http://www.haskell.org/ghc/  :? for help
    Loading package ghc-prim ... linking ... done.
    Loading package integer ... linking ... done.
    Loading package base ... linking ... done.
    [1 of 1] Compiling Main             ( A.hs, interpreted )
    Ok, modules loaded: Main.

    *Main> :t main
    main :: IO ()

You should give any error message, and the steps you took that lead to
the error when making a bug report.

-- Don