I am trying to write some code to read flat files from a mainframe system. This includes some character fields. This is a fixed width file, so each field will have a consistent length between records, but there are fields of different length within a record. For example, I might have a "name" field length 20 and an eye color field length 5.

I am trying to use the binary library to read in this file. I've written a binary type, MFChar2, for reading in a 2-length character field. It is defined as such (you can safely ignore the ebcdicToAscii piece, it is just doing character conversion):

data MFChar2 = MFChar2 [Word8]
instance Binary MFChar2 where
    put = undefined
    get = do ebcdic <- replicateM 2 getWord8
             return $ MFChar2 $ map ebcdicToAscii ebcdic

What I would like to do is have some kind of generic "MFChar" data type which could take any character length, but I can't figure out how to do it. Any help would be appreciated.

Thanks,
Michael