On Fri, Feb 29, 2008 at 1:31 AM, Tobia Conforto <[EMAIL PROTECTED]> wrote: > Graham Fawcett wrote: > > There does seem to be a good case for an immediate value that *can* > > be tested this way, though. John et. al. wouldn't have used (void) > > in eggs if there weren't. > > What about providing a utility to create new immediate values, > disjoint from anything else? > > The immediate value space is far from cramped, if I'm not mistaken. > Such a new-immediate-value function (which could benefit from a better > name) would return a new value every time it's called, using for > example an internal counter. One could write: > > (define sql-null (new-immediate-value)) > > (define (sql-null? x) (eq? x sql-null)) > > With the certainty that sql-null won't be eq? to anything else at all, > won't be a list, a record, nothing at all except itself. > > I think this could have a few uses. (Unless it's terribly broken in a > way I can't see, which is quite possible :-) >
It would probably have uses, but what would you gain? All you need is a distinct unique object: (define sql-null (gensym 'sql-null)) cheers, felix _______________________________________________ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
