Supporting non-string inputs

I have another, more complex question. Would you be open to the idea of supporting inputs which are not strings?

The main thing I'd like to have is a list of terms as input. Basically, I'd like to use say `leex` to tokenize the input, and then `combine` to work on the grammar. Currently, the code is a bit clunky for more complex grammars, since tokenizing and parsing is conflated. For example, working with whitespaces is a bit hard, because we need to ignore them in many different places.

So the question is would you consider such option?

I'll cc my colleague @obrok here, as he also might find this discussion interesting :-)