[plt-scheme] Re: String equality and other questions

Thanks for the speedy fix!

On Sep 25, 1:21 am, Matthew Flatt <mfl... at cs.utah.edu> wrote:
> Thanks for sending me some code.
>
> Your program imports SRFI 63, which apparently provides its own
> `equal?' that is shadowing the usual one. (I noticed this by clicking
> Check Syntax in DrScheme and then mousing over the `equal?' identifier
> in your program.)
>
> The `equal?' in the SRFI 63 implementation, meanwhile, seems to have
> been completely broken. I committed a repair to SVN.
>
> Matthew
>
> At Wed, 24 Sep 2008 06:02:49 -0700, Matthew Flatt wrote:
>
>
>
> > At Tue, 23 Sep 2008 21:25:26 -0700 (PDT), Deep wrote:
> > > While writing a game in scheme I recently ran into an issue where
> > > using equal? to compare strings would wait on the equality test and
> > > hog the cpu 60-70% of the time.  Oddly enough it worked sometimes. I
> > > looked through my code suspecting a recursive call gone amuck but
> > > eventually narrowed the issue down to this call.  I had unfortunately
> > > run intohttp://www.federated.com/~jim/schintro-v14/schintro_102.html
> > > when searching for "scheme string equality" and used equal?.
>
> > > Once I looked again and changed the code to use string=? things work
> > > just fine. I wanted to know what does equal? do when used against
> > > strings. Why does it work sometimes and why does it just hang on other
> > > occasions?
>
> > As Eli says, that's a surprising result. The `equal?' function is
> > commonly used on strings, and assuming that you're using a language
> > like `scheme/base', R5RS, or R6RS (all the same `equal?'), then
> > `equal?' fairly quickly determines when it's given strings and then
> > does the same thing as `string=?'.
>
> > If your program is something that you can send to me, then I'm
> > interested to try it myself (with `equal?' in place of `string=?').
>
> > Matthew
>
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