[\'\`] $ident+ [\'\`] { ident }
\\ . { strtoken (TokString . tail) }
"&#" $digit+ \; { strtoken $ \s -> TokString [chr (read (init (drop 2 s)))] }
"&#" [xX] $hexdigit+ \; { strtoken $ \s -> case readHex (init (drop 3 s)) of [(n,_)] -> TokString [chr n] }
-- allow special characters through if they don't fit one of the previous
-- patterns.
[\'\`] $ident+ [\'\`] { ident }
\\ . { strtoken (TokString . tail) }
"&#" $digit+ \; { strtoken $ \s -> TokString [chr (read (init (drop 2 s)))] }
"&#" [xX] $hexdigit+ \; { strtoken $ \s -> case readHex (init (drop 3 s)) of [(n,_)] -> TokString [chr n] }
-- allow special characters through if they don't fit one of the previous
-- patterns.