In article <··········@pandora.sdsu.edu> ········@ucssun1.sdsu.edu (Yuan-chi (Bill) Chiu) writes:
> I'm somewhat new in the field of Common Lisp programming language. I have
>done some works with it, but often I run into problems where there are
>no buildin Lisp function to deal with them. I will list some of them:
Common Lisp has lots of built-in functions for dealing with homogeneous
lists, but not many for dealing with trees. The only tree functions I can
think of offhand are COPY-TREE, SUBST, and SUBST-IF. EQUAL could also be
thought of as a tree function.
In general, it doesn't seem common to need to treat all levels of a tree
equivalently. Each level of a tree usually represents something different.
Your examples look like the kinds of problems that come up in academic
exercises, but not in the real world.
--
Barry Margolin
System Manager, Thinking Machines Corp.
······@think.com {uunet,harvard}!think!barmar