I noticed that the current definition of the POSIX "graph" character class is written as: https://github.com/haskell-hvr/regex-tdfa/blob/0392ea07fe3b4555265104d64727d55086835af1/lib/Text/Regex/TDFA/Pattern.hs#L204 According to the [Wikibooks: Regular Expressions - POSIX Basic Regular Expressions](https://en.wikibooks.org/wiki/Regular_Expressions/POSIX_Basic_Regular_Expressions), the `[:graph:]` character class is equivalent to `[^ [:cntrl:]]`. So "graph" class should cover characters from decimal 33 through 126.