On 1/12/12 2:48 PM, Jordan Johnson wrote:
Hi all,
A student presented me this morning with an implementation he'd written of
Pong, which, after about a minute and a half of running (in BSL) was so slow on
his Mac that it was unusable; specifically, the apparent speed slowed down a
lot, and the game stopped responding to key input. I found the same thing
happened on Win 7, but if I ran the same program under #lang racket, no such
slowdown occurred. It appears that there's some memory growth over time (maybe
about 1K per five or ten seconds) in BSL too.
What language difference(s) might be responsible for the vast performance
difference we're observing? If it would be helpful to see the code I can share
it, but it's about 1000 LoC and I don't think it's proper to post it publicly.
I've tried to construct a small program that shows the same difference, but
haven't managed; I don't, however, see anything in his code that would be
obviously responsible.
Thanks for any insight you might be able to offer.
I bet it's exact arithmetic. Racket sees 1.2 as an inexact number,
while *SL sees it as exact. Try inserting "#i" before any literal
numbers in the code and see if that does the trick.
David
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