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Re: [Chicken-users] New immediate values (was: DBI)
From: |
felix winkelmann |
Subject: |
Re: [Chicken-users] New immediate values (was: DBI) |
Date: |
Fri, 29 Feb 2008 12:54:56 +0100 |
On Fri, Feb 29, 2008 at 1:31 AM, Tobia Conforto <address@hidden> 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
- Re: void as a return value (Re: [Chicken-users] DBI), (continued)
- 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
- Re: [Chicken-users] New immediate values (was: DBI), John Cowan, 2008/02/28
- Re: [Chicken-users] New immediate values (was: DBI), Mario Domenech Goulart, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI),
felix winkelmann <=
- Re: [Chicken-users] New immediate values (was: DBI), Tobia Conforto, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), felix winkelmann, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), Graham Fawcett, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), Tobia Conforto, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), Graham Fawcett, 2008/02/29
- Re: [Chicken-users] New immediate values, Ozzi Lee, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), John Cowan, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), felix winkelmann, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), Alaric Snell-Pym, 2008/02/29
- Re: [Chicken-users] New immediate values (was: DBI), John Cowan, 2008/02/29