Re: Collection operations taking pseudo-predicates?

[Hugh Greene <address@hidden*.com>]

Bruce Hoult wrote:
> In article <3C986B2E.B8FA6711@lucent.com>,
>  Gabor Greif <ggreif@lucent.com> wrote:
>>http://www.gwydiondylan.org/drm/drm_102.htm#HEADING102-0
>>
>>states under
>>
>>	choose [Open Generic Function]
>>	...
>>	Returns a sequence containing those elements of source-sequence that satisfy 
>>predicate.
>>	...
>>
>>
>>I wonder if a proper predicate is needed (i.e. one returning a <boolean>) or 
>>a pseudo-predicate
>>( whose result is compared against #f) is sufficient.
>>
>>
>>Anybody who can shed light on this?
>>
> 
> This is a theoretical question?
> ...

The main question is usually whether one can find the answer in the DRM 
before giving up in despair at it's complicated structure ;-)  In this case,

http://www.gwydiondylan.org/drm/drm_33.htm#HEADING33-105

says

     For the purposes of conditional execution, there is a single object
     that counts as false [i.e., #f], and all other objects count as true.

HTH,
Hugh