🚀 go-pugleaf

In article <benanav.686887869@earth.njit.edu> benanav@earth.njit.edu (Dan Benanav) writes:

   clin@eng.umd.edu (Charles Lin) writes:

   >    While I personally like the idea of recursion and use it whenever I program
   >in LISP, I am curious to other reasons of using recursion besides elegance.


   It's not just a matter of elegance.  I find it much easier to write
   resursive programs.   I can write a recursive version of an
   algorithm  much faster then the iterative version.

I've just been working away on a hand-proven program (anyone still
remember me promising to have a TR about doing this?  I'm *finally*
getting around to finishing it.  Don't ask why.)  and, anyway, noticed
something rather neat: often, I can use a recursive program to identify
the appropriate bound and invariant for an iterative program; of course,
once one has both coding the loop itself is trivial.  (Except when it
isn't, of course.)

In any case, I suspect that which is more "natural" is largely based on
experience, and often depends on what your first experience was.  If you
-- as I did -- wrote your first tree-searching routines in Fortran II,
you will probably always have an inclination to use iteration;
similarly, if you grew up in a Lisp environment, you will gravitate to
recursion.  I also share Dijkstra's distaste for a fixation on recursion
so strong that the definition of a while..do is resolved to be a
recursive call.

In any case, I think that it's incumbent on programmers to try to learn
to use BOTH recursion and iteration naturally and readily, so that
both are available parts of the tool bix.
--
Charles R. Martin/(Charlie)/martinc@cs.unc.edu/(nee crm@cs.duke.edu) 
O/Department of Computer Science/Sitterson Hall/UNC/Chapel Hill, NC 27599
H/13 Gorham Place/Durham, NC 27705/(919) 383-2256
		"This universe is full of magical things
	    patiently waiting for our wits to grow sharper"