[Haskell-cafe] GADT vs Arrows for parsers/FSMs/etc.

[Neil Mitchell]

Hi

> It seems like Haskell has two emerging idioms for parsing and fsms:
> GADTs and Arrows.

What about something else? If you limit yourself to the two things
that look "new and cool" (where emerging is another word for new, and
idiom seems to be the current Haskell word for cool), you miss out on
all the tried and tested stuff.

> I am thinking about using one of these idioms to represent server
> structure in a future version of HAppS but I'm not sure where to
> start.  Why would one choose one or the other?

I would pick Arrows (over GADTs) because Arrows are Haskell, and are
supported by multiple Haskell compilers. Other than that (as far as I
was aware) these two things are massively different, so I wouldn't
have thought it was a "one or the other" choice usually.

Thanks

Neil