On Tue, Nov 20, 2012 at 07:42:46AM -0600, Robby Findler wrote: > On Tue, Nov 20, 2012 at 12:14 AM, David T. Pierson <d...@mindstory.com> wrote: > > On Mon, Nov 19, 2012 at 06:13:09AM -0700, Matthew Flatt wrote: > >> Should we change `case' to use `equal?' instead of `eqv?'? I can't > >> think of a good reason to stick with `eqv?'. > > > > My first reaction to this was that such a change would eliminate one of > > the motivations for using `case': getting the (perhaps insignificant?) > > performance improvement of using `eqv?' in a conditional when you know > > the key type is suitable for it. > > > > However it occurs to me that since the datums in a `case' clause are > > always literals, couldn't the expansion of `case' be "smart" enough to > > use the appropriate comparison function (eq?/eqv?/equal?) given the type > > of the datum? > > I think that equal? will always terminate quickly when its input is a > symbol/number/boolean so the macro doesn't need to do anything special > in that case.
It could do a binary tree search on the data and use some kind of ordering comnparison. By the way, it's a long time since I saw 'datums' as plural of 'datum'. I wonder if it will become correct one of these years, since 'data' is often misused as singular, as a substance noun instead of an object noun. -- hendrik ____________________ Racket Users list: http://lists.racket-lang.org/users
