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Re: [Chicken-users] DBI
From: |
Graham Fawcett |
Subject: |
Re: [Chicken-users] DBI |
Date: |
Wed, 27 Feb 2008 16:35:46 -0500 |
On Wed, Feb 27, 2008 at 4:31 PM, Peter Bex <address@hidden> wrote:
> 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".
(void) returns the unspecified value, in Chicken, #<unspecified> -- as
does (values). But the unspecified value is a value, and can be tested
for identity with eq?.
> (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.
It's an implementation detail of Chicken, but it is highly unlikely
that it will change. Void is nebulous as a concept, but its Chicken
implementation is concrete.
Graham
- [Chicken-users] DBI, Ozzi Lee, 2008/02/27
- Re: [Chicken-users] DBI, John Cowan, 2008/02/27
- Re: [Chicken-users] DBI, Ozzi Lee, 2008/02/27
- Re: [Chicken-users] DBI, Jeremy Sydik, 2008/02/27
- void as a return value (Re: [Chicken-users] DBI), Vincent Manis, 2008/02/27
- Re: void as a return value (Re: [Chicken-users] DBI), Ozzi, 2008/02/27
- Re: void as a return value (Re: [Chicken-users] DBI), John Cowan, 2008/02/27
- Re: void as a return value (Re: [Chicken-users] DBI), Vincent Manis, 2008/02/27
- Re: [Chicken-users] DBI, John Cowan, 2008/02/27
- Re: [Chicken-users] DBI, felix winkelmann, 2008/02/28
- Re: [Chicken-users] DBI, Graham Fawcett, 2008/02/28
- [Chicken-users] New immediate values (was: DBI), Tobia Conforto, 2008/02/28
- Re: [Chicken-users] New immediate values (was: DBI), Graham Fawcett, 2008/02/28