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From: kanamori@Neon.Stanford.EDU (Atsushi Kanamori)
Newsgroups: comp.edu
Subject: Re: ALGORITHMS ANYBODY?
Message-ID: <1990Aug23.161305.24777@Neon.Stanford.EDU>
Date: 23 Aug 90 16:13:05 GMT
References: <90Aug22.090345edt.9450@neat.cs.toronto.edu> <4147@iitmax.IIT.EDU>
Organization: Computer Science Department, Stanford University
Lines: 38

In article <4147@iitmax.IIT.EDU> draughn@iitmax.iit.edu (Mark Draughn) writes:
>In article <90Aug22.090345edt.9450@neat.cs.toronto.edu> mgreen@cs.toronto.edu (Marc Green) writes:
>[...]
>>I've decided to center the course of the view that computer languages
>>are a way to formally specify algorithms. I'd like the students to
>>program the same 3-4 algorithms in several languages, to get a feel
>>for the differences.
>[...]
>>I have in mind algorithms like bubble-sort, merge-sort, tree-search
>>and problems like the Tower of Hanoi. Any others?
>

>
>Seriously, maybe I'm misunderstanding you, but this plan of yours
>sounds a bit boring.  These algorithms look about the same in almost
>all languages.  Sure, LISP recursions and FORTRAN loops look
>different, but what do you do after that?
>

I think the intended approach was to disallow side-effects in Lisp;
then the difference between Lisp sorters and Fortran sorters are a lot
more than just syntactic.

In general, the fun part of this approach is choosing problems that
require a nontrivial amount of head-scratching to implement in each language.
It might help if we try to think in terms of problems rather than algorithms;
fixing the algorithm tends to fix the programming paradigm (i.e. some
algorithms are naturally Fortran-ish and others are naturally Lisp-ish)
and I believe the intent is to force the student to think in the different
paradigms of each language.

BTW: Don't use Towers of Hanoi; it may be a classical example of
recursion but there is an obscure iterative solution: if a student
happens to know this, you'll have a horny policy problem on your hands.
Tree-search is pretty good as a method of comparing the dynamic-data-structure
abilities of different languages. You might also consider a companion
problem in which data structures shrink as well as grow (i.e. show
how garbage collectors make one's life easier.)