On Wed, Feb 27, 2008 at 04:23:37PM -0500, Graham Fawcett wrote: > > Can you even check for void? Afaik there's no VOID? procedure. > > You can; just compare with another (void) value: > > (define void? (cute eq? (void) <>))
That sounds rather brittle. Afaik "void" is defined as "no value". One possible and plausible implementation of VOID is this: (define (void) (values)) (eq? (values) (values)) is #t, but I'm not sure how safe it is to depend on that. Especially since VOID is some kind of "undefined" value, nobody says this representation can't change. I don't think you should depend on this implementation detail. Cheers, Peter -- http://sjamaan.ath.cx -- "The process of preparing programs for a digital computer is especially attractive, not only because it can be economically and scientifically rewarding, but also because it can be an aesthetic experience much like composing poetry or music." -- Donald Knuth
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