[cdr-discuss] Three RFCs

[Pascal Costanza]

On 16 Mar 2008, at 14:57, Leslie P. Polzer wrote:

>
> Hello folks,
>
> here are three CDR ideas that I would like to get your comments on:
>
> 1. Support a :TEST arg for (E)CASE.

I'm not sure what this buys you over a regular cond. Case primarily  
exists for efficiency, no?

> 2. Setup BACKQUOTE to be the backquote expansion object. I believe  
> this
>   is common implementor's practice.

It would indeed be good if it were standardized what the ` , and ,@  
expand into. However, this should take into account current practice,  
so would need an analysis stage first, I think. This sounds like hard  
work (but maybe I'm overestimating this).

Whether it's common already or not doesn't matter that much. Those  
implementations that don't want to implement the CDR don't implement  
the CDR.

> 3. Support extended feature tests. It would be nice to be able to say
>   +(find-package 'zoo)(...)

I don't think that's a good idea because it changes the semantics of  
boolean expressions. (when :some-keyword (print 'foo)) will always  
print 'foo, whereas #+some-keyword (print 'foo) prints 'foo only  
if :some-keyword is on the feature list. In other words, this may lead  
to some unexpected results.

What's wrong with this?

#.(if (find-package 'zoo)
     '(do-this ...)
     '(do-that ...))


Pascal

-- 
1st European Lisp Symposium (ELS'08)
http://prog.vub.ac.be/~pcostanza/els08/

Pascal Costanza, mailto:pc at p-cos.net, http://p-cos.net
Vrije Universiteit Brussel, Programming Technology Lab
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