[cdr-discuss] Three RFCs

[Pascal Costanza]

On 18 Mar 2008, at 10:46, Leslie P. Polzer wrote:

>
> Hello Pascal,
>
> thanks for your comments.
>
>>> 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?
>
> Clarity of semantics. As Gary already pointed out somewhat,
> COND models “branch according to arbitrary predicates”,
> while CASE models “branch according to equality of a variable
> binding”.
>
> But an extended CASE would also, by way of this semantical difference,
> extend the efficiency by letting the compiler optimize it (e.g.
> via hash tables). This is hardly possible with a COND).

Well, I think it is, but I see your point better now.

>> 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).
>
> Why do you think so?

...because I recall reading that the semantics of backquote is not so  
straightforward, and my experience with other constructs in Common  
Lisp (and other languages for that matter) shows that the devil is in  
the details.


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
Pleinlaan 2, B-1050 Brussel, Belgium