Jonathan Roewen wrote:

> 
> Ideas on whether this is a good design, and what would probably be the
> best way to do this are welcome =)

I think, from an "external" point of view in the sense that I never did such
things, that using arrows should be a good idea. Perhaps the following is a
good index/starting point for such concepts, in particular the papers
related to Fran and Yampa:

http://www.cs.uu.nl/wiki/Afp/DomainSpecificLanguages

V.

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