GHCi ignores {-# LANGUAGE OverloadedStrings #-}

Very simple test file like:

{-# LANGUAGE OverloadedStrings #-}

import Data.ByteString                     (ByteString)
import qualified Data.ByteString.Char8     as BS

newlineCount :: ByteString -> Int
newlineCount bs = BS.foldl foldFun 0 bs
   where foldFun s ch = if ch == '\n' then s + 1 else s

main :: IO ()
main = print $ newlineCount "a\nb\nc\n"

If I load this into GHCi, I can run the main function, but if I try to run newlineCount with a string I provide, I get an error:

erikd@pharoah > ghci test.hs 
GHCi, version 7.0.4: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
[1 of 1] Compiling Main             ( test.hs, interpreted )
Ok, modules loaded: Main.
*Main> main
Loading package bytestring-0.9.1.10 ... linking ... done.
3
*Main> newlineCount "a\nb\nc\n"

<interactive>:1:14:
    Couldn't match expected type `ByteString' with actual type `[Char]'
    In the first argument of `newlineCount', namely `"a\nb\nc\n"'
    In the expression: newlineCount "a\nb\nc\n"
    In an equation for `it': it = newlineCount "a\nb\nc\n"

which is rather unexpected.

Trac metadata

Trac field	Value
Version	7.0.4
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	GHCi
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