On Mar 9, 2012, at 6:25 AM, Rüdiger Asche wrote: > (define (vendingmachine currentstate) > (let ((newstate > (case currentstate > [(VENDINGMACHINE_IDLE) > (if (CoinInserted) > VENDINGMACHINE_INSERTED_COIN > VENDINGMACHINE_IDLE > ) > ] > [(VENDINGMACHINE_INSERTED_COIN) > ... > ... > > where every of the VENDINGMACHINE_xxx identifiers is very simply a readable > symbolic identifier for a disjoint constant. I have a hard time believing > that in reasonably complex fsms, it shouldn't impose a severe performance > penalty to look up a constant every time it is used?
Why not just use symbols for these, without worrying about what they "stand for"? If you've implemented a Scheme system, you know about interned symbols: the symbol-table lookup should happen at compile-time (right?), so you're left with a constant-time pointer comparison at run-time. Disclaimer: I've implemented only "toy"-scale Schemes myself. Stephen Bloch sbl...@adelphi.edu ____________________ Racket Users list: http://lists.racket-lang.org/users
