Re: void as a return value (Re: [Chicken-users] DBI)

[Vincent Manis]

On 2008 Feb 27, at 19:17, John Cowan wrote, quoting me:

> > alternatively, an object called the-SQL-null-object could be created
> > (perhaps as a record type value).
>
> That is a priori reasonable, but it won't work with eq?, whereas the
> unspecified value will.
I fail to understand why eq? compatibility is significant, one provides
a predicate to test SQL null-ness.

In order to sort out this farrago of nothingness, let me suggest the  
following:

a. '() is just right for a multivalued field that happens to contain no
   values, but is unsuitable for indicating SQL null.
b. (the-SQL-null-object) returns an SQL null value, and (SQL-null? x)
   tells you whether x is an SQL null. (I'm not wedded to those names,
   just using them as an example.)
c. Whether (the-SQL-null-object) returns a value of a disjoint type
   from that returned by (void) is theoretically unimportant, but
   it would be more elegant and explainable if the return value
   behaves in a manner that's consistent with #!eof.

-- vincent