🚀 go-pugleaf

In article <1991Oct04.142838.29652@eng.umd.edu> clin@eng.umd.edu (Charles Lin) writes:

> [...] For example, in Pascal,
>a beginner might ask what happens to the original variable values passed in
>when a recursive call is made.  It is useful, to my mind, to say that the
>function "stores" away these values for later use.  But then, perhaps, I, too,
>have been brainwashed by the process.

Yes, you've been a bit "brainwashed" by thinking of variables as boxes in
which to store things.  The way I explain it to beginners is that the machine
creates "a new copy" of the procedure, containing the same instructions but
totally non-conflicting variables. (Actually only the stack frame is copied,
but that's a detail of implementation.)  The procedure says _how_ to do
things; the storage of variables is a separate issue.

Recursion is easier to introduce using examples where there are no variables
except for the arguments to procedures.  This kind of example is more
abundant in Prolog and Lisp than in other languages.



-- 
==================================================================
Michael A. Covington, Ph.D.  |  mcovingt@uga.cc.uga.edu   |  N4TMI
Assistant to the Director, Artificial Intelligence Programs
The University of Georgia, Athens, Georgia 30602, U.S.A.