Am Donnerstag, 29. Januar 2009 16:25 schrieb emmanuel.delaborde:
Hello
I have the following snippet :
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module Main where
import System.Environment (getArgs) import Data.Digest.OpenSSL.MD5 (md5sum) import Data.Digest.Pure.SHA (sha1, showDigest) import qualified Data.ByteString as BS (readFile)
-- sha1 :: ByteString -> Digest -- readFile :: FilePath -> IO ByteString -- md5sum :: ByteString -> String -- showDigest :: Digest -> String
checkHash :: String -> String -> String -> IO () checkHash codec hash file = let f = case codec of --"md5" -> md5sum "sha1" -> showDigest . sha1 _ -> error "Codec must be md5 or sha1 !" in BS.readFile file >>= \fileBS -> let fileHash = f fileBS in print (hash == fileHash)
main = getArgs >>= \as -> case as of (codec:hash:file:_) -> checkHash codec hash file _ -> usage
usage = print "checksum codec hash file"
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which fails to compile, this is the error I get :
checksum.hs:20:19: Couldn't match expected type `Data.ByteString.Lazy.Internal.ByteString' against inferred type `Data.ByteString.Internal.ByteString' In the first argument of `f', namely `fileBS' In the expression: f fileBS In the definition of `fileHash': fileHash = f fileBS
it looks like (showDigest . sha1) expects Data.ByteString.Lazy.Internal.ByteString but gets Data.ByteString.Internal.ByteString
What can I do ?
import qualified Data.ByteString.Lazy as BS (readFile) should do it.
Thanks
E.
Cheers, Daniel