Re: Using Macros in Lisp

[Vincent Keunen <keunen@milou.nrb.be>]

Right.  But unlike most other macro mechanisms in other languages, the
macro mechanism in lisp isn't a simple text substitution.  It is
actually a lisp program that is evaluated at compile time to generate
the final source that will be evaluated.  That's why lots of people talk
about "double evaluation", which is not wrong.
 
Although I'm not sure and have no example, I would tend to believe that
there are *some* things that are impossible to do without macros (apart
from the non-evaluatiuon of arguments).  Admitedly, these are really
special cases, but the meta-real-cool lisp programmers could maybe give
an example.
 
 
Vincent Keunen