On Fri, 29 Feb 2008 01:31:38 +0100 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. Wouldn't define-record do the trick? Best wishes, Mario _______________________________________________ Chicken-users mailing list [email protected] http://lists.nongnu.org/mailman/listinfo/chicken-users
