Hello I would change you Alex specification to this: $digit = 0-9 -- digits $alpha = [a-zA-Z] -- alphabetic characters $eol = [\r\n] $any = [^$eol] tokens :- $eol { tok $ \_ -> Eol } $any+ { tok $ \s -> Str s } The complementation operator (^) works of character sets so I don't expect your original formulation to work: $any = [^\r\n] (maybe it should, but I never liked the Alex syntax...) You can test alex scanners like this: demo01 = alexScanTokens "happy?\n" demo02 = readFile "sample" >>= print . alexScanTokens Note - your sample file is using extended characters so it fails for me with Alex 2.3.2. I'm now sure how capable the current version of Alex is or whether better Unicode support can be enabled with flags. Regards Stephen