One way is to just write:
(define (my-big-bang ht) (big-bang [on-tick (hash-ref ht 'on-tick)]
...etcetcetc...))
and you'd be duplicating the default values but maybe that's enough to get
going for now?
Robby
On Sun, Apr 21, 2013 at 10:04 AM, Joe Gibbs Politz <j...@cs.brown.edu> wrote:
> I'd like to write a library function that takes a hash table of
> handlers and starts a running world in big-bang style, for example:
>
> (my-big-bang
> 0
> (make-immutable-hash
> `((on-tick . ,add1)
> (stop-when . ,(lambda (x) (> x 100))))))
>
> Is there an interface that I could use to write this? I suppose I
> could try to generate a syntax object containing an appropriate
> big-bang and eval it, but that seems like a big hammer to wield here.
> I've poked around a little bit in 2htdp/ but haven't found anything
> provided that seems to fit the bill.
>
> Motivation: I want to support big-bang in a language that doesn't
> support macros (yet), and I don't want to add special-case syntax for
> big-bang. I'd like the usage in that language (Pyret, which has
> Python-like syntax) to look like:
>
> big-bang(init, {
> event_name: event_handler,
> ...
> })
>
> Which calls something like `my-big-bang` under the hood.
>
> Thanks!
> Joe
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