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Re: A macro and an unwanted containing list in the resulting form


From: Sebastian Tennant
Subject: Re: A macro and an unwanted containing list in the resulting form
Date: Thu, 24 May 2007 16:49:10 +0300
User-agent: Gnus/5.110006 (No Gnus v0.6) Emacs/22.0.95 (gnu/linux)

Quoth Tim X <address@hidden>:
>>> (require 'cl)
>>>
>>> (defun my-function (string clauses)
>>>   (loop
>>>       for clause in clauses
>>>       until (string= string (car clause))
>>>       finally (eval (cdr clause))))
>>>
>>> (my-function "goodbye" '(("hello"   . (message "hi"))
>>>                          ("goodbye" . (message "bye"))))
>>>
>>
>> Whoa!  This isn't LISP!  At least it doesn't look like it to me.
>> Where are the parentheses?  I suppose I haven't got the first idea how
>> the Common Lisp 'loop' function works...???
>>
>> Sebastian
>>
> You aren't the first to make those comments. CL's loop is one area
> that generally creates considerable debate - som argue its not lispy
> and is difficult to master. Others argue its a very powerful
> construct that shows what you can do with CL.
>
> I'm still pretty much a novice with CL and will admit that loop and
> format (the CL version) are two aspects of CL that took considerably
> more mental effort to understand. I now now reasonably confident
> with using format, though I constantly have to check the
> references. Loop on the other hand is still a concept I get amazed
> by and one I have a lot more work to do with before I can honestly
> say I'm confident with. However, like most of the stuff I've done
> with CL, its been one of the most rewarding languages I've learnt
> for many many years. I also find the different development style of
> working in CL extremely rewarding after years of C, C++, Java, Tcl
> and Perl. I now find I've gotten to the point that its productive
> for me to 'explore' a problem with CL before I start implementing
> the solution in another (more readily accepted) language.  This
> process often exposes subtle issue that are not evident when working
> on a solution from an abstract level and I'm finding it saves me
> time refactoring or redesigning things to accomadate the increased
> understanding that occurs as you work on a problem.

Sounds like CL is definitely something worth exploring (there are _so_
many things worth exploring) but it'll have to wait for another day.
I'm happy with my new-found grasp of macro-expansion for the time
being!

Sebastian





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