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> Eric Lind wrote:
> > recursion - the process of one function calling itself to solve a problem.
> > This is done by breaking the problem down to its smallest size, then • combining
> > the smaller solutions. Factorials are usually used as a simple example of
> > recursion. 6! = 6*5*4*3*2*1. One can repeatedly break the factorial down
> > until you reach 1, then recombine the problem to find the final solution.
You might want to add the recursive part of this example
(namely 6! = 6*(5!), and 5! = 5*(4!), and so on,
until you get 1!, which is equal to 1. Then you travel
back up the chain, multiplying as you go).
Later,
Blake.
--
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Subject:
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Scheme
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 11 May 1999 11:17:17 GMT
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Original-From:
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Rich Clemens <[clemens@wvwc.edu]AvoidSpam[]>
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Anyone consider scheme as a "language" to drive RCX?
--
Richard Clemens
Associate Professor
Computer Science Department
West Virginia Wesleyan College
Buckhannon, West Virginia 26201
clemens@wvwc.edu
304.473.8421
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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At 05:44 PM 5/10/99 -0400, Blake Winton wrote:
>
> > Eric Lind wrote:
> > > recursion - the process of one function calling itself to solve a • problem.
>
> You might want to add the recursive part of this example
> (namely 6! = 6*(5!), and 5! = 5*(4!), and so on,
You know, I have never really liked the factorial example of recursion.
Honestly, how many times have you really needed to generate a factorial in
general experience?
I feel a better example is building stuff with LEGO. In this case, you are
the function and the LEGO is the data.
The basic function you perform is sticking blocks together. So to build a
rocket ship, you first need to attach the body to the engine. To build the
engine you need to attach the intake to the exhaust, and so on. As you
progress, you may be generating very complex items, but you are still
performing the same basic action, attaching one block to another.
Aloha,
JR
- - - - - - - - - -
JR Conlin jrconlin@email.com
Techno-Athiest yahooPage: jrconlin
<http://home.earthlink.net/~jrconlin>
--
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Subject:
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Re: Scheme
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 11 May 1999 15:12:17 GMT
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Original-From:
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Joel Shafer <joel@STOPSPAMMERSconnect.net>
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Could you give a brief description of scheme? I've heard that it is a
fairly high level language and I know that a compiler or interpreter exists
for it on linux.
At 07:17 AM 5/11/99 -0400, you wrote:
> Anyone consider scheme as a "language" to drive RCX?
> --
> Richard Clemens
> Associate Professor
> Computer Science Department
> West Virginia Wesleyan College
> Buckhannon, West Virginia 26201
> clemens@wvwc.edu
> 304.473.8421
>
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
Joel Shafer joel@connect.net
--
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Subject:
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Re: Scheme
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Newsgroups:
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lugnet.robotics
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Date:
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Tue, 11 May 1999 16:12:07 GMT
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Original-From:
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Alex Wetmore <alex@phred/saynotospam/.org>
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From: Joel Shafer <joel@connect.net>
> Could you give a brief description of scheme? I've heard that it is a
> fairly high level language and I know that a compiler or interpreter • exists
> for it on linux.
http://www.scheme.org/
In my view Scheme is the most useful subset of lisp, designed to make a
small, elegant, functional language. This is compared to Common Lisp, which
is kind of a superset of the various lisp-dialects, meant to contain
everything.
Note: I am not a lisp-expert, I just used Scheme in one of my university
classes, and have played around with Common-lisp a little bit. I would
probably recommend playing around with PbForth on the RCX. Forth is a
lightweight, interpreted, stack-based language. It doesn't have lambda
functions (I don't think it does at least), but has a similar sort of
environment to most scheme systems (you can type directly into the
interpreter).
alex
--
Did you check the web site first?: http://www.crynwr.com/lego-robotics
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Ah, er, right. I forgot that bit. I was sorta in a hurry to get to class and
I didn't elaborate my example. My bad. You're quite right.
In lugnet.robotics, lego-robotics@crynwr.com (Blake Winton) writes:
> You might want to add the recursive part of this example
> (namely 6! = 6*(5!), and 5! = 5*(4!), and so on,
> until you get 1!, which is equal to 1. Then you travel
> back up the chain, multiplying as you go).
>
> Later,
> Blake.
>
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
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It strikes me that Scheme is largely an academic language. Granted, there are
a few Scheme devotees out there who worship the language, but they seem to be
all at MIT or Rice. I think they've even written modules for web programming
with Scheme, but I have to wonder what psychotropic drugs they were on when
they did it. Scheme, like most functional languages, is based on functions.
One doesn't store values in variables, you have a function that returns the
value, which is then piped into another function, etc. I have to say I learned
recursion really well from it (as there are no iterative constructs, all
looping is done via recursion), but I wouldn't want to use it in daily life. I
don't think it's appropriate for the RCX (to bring this back to oblego), as it
is a pure interpreted language and the stack costs for it would be huge.
In lugnet.robotics, Alex Wetmore writes:
> From: Joel Shafer <joel@connect.net>
> > Could you give a brief description of scheme? I've heard that it is a
> > fairly high level language and I know that a compiler or interpreter • exists
> > for it on linux.
>
> http://www.scheme.org/
>
> In my view Scheme is the most useful subset of lisp, designed to make a
> small, elegant, functional language. This is compared to Common Lisp, which
> is kind of a superset of the various lisp-dialects, meant to contain
> everything.
>
> Note: I am not a lisp-expert, I just used Scheme in one of my university
> classes, and have played around with Common-lisp a little bit. I would
> probably recommend playing around with PbForth on the RCX. Forth is a
> lightweight, interpreted, stack-based language. It doesn't have lambda
> functions (I don't think it does at least), but has a similar sort of
> environment to most scheme systems (you can type directly into the
> interpreter).
>
> alex
>
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
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JR Conlin <jrconlin@email.com> wrote:
> You know, I have never really liked the factorial example of recursion.
> Honestly, how many times have you really needed to generate a factorial in
> general experience?
The factorial is useful for probability.
The factorial is a simple, understandable example of recursion, useful to
teach the concept; it is lacking only in that it is not very efficient.
But when you are first learning, I think concepts are more important than
efficiency.
Good examples of where recursion is actually useful are:
- ray tracing
- solving Towers of Hanoi
Not that these help explain the concept, though.
-Kekoa
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Kekoa Proudfoot wrote:
> Good examples of where recursion is actually useful are:
>
> - ray tracing
> - solving Towers of Hanoi
You know, a 'bot that actually solves a Towers of Hanoi puzzle with real plates
and whatnot would be a pretty cool challenge on hardware like the RCX.
(ponder, ponder, ponder)...
I don't think it's possible with anything less than LegOS or pbForth though.
> > Mark
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In article <37389556.ACC65587@lynx.bc.ca>, Mark Tarrabain
<markt@lynx.bc.ca> writes
> You know, a 'bot that actually solves a Towers of Hanoi puzzle with real plates
> and whatnot would be a pretty cool challenge on hardware like the RCX.
I saw one of the early pumas playing hanoi at an exhibition. It must be
arout 30 years ago - it's been done before.
--
Regards - Peter Hesketh, Mynyddbach, Mon.
Forty reasons why a dog is better than a woman: number 44
"A dog doesn't tell you you need a haircut."
That's the lot, folks: the complete set is available from
http://www.phesk.demon.co.uk/dg1-44.zip
--
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Subject:
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Re: Scheme
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Newsgroups:
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lugnet.robotics
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Date:
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Wed, 12 May 1999 03:26:18 GMT
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Original-From:
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Rich Clemens <clemens@*spamless*wvwc.edu>
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A simple scheme interface such as (sensor <num> <type> <mode>) or (motor
<letter> <direction> <speed>) could prove a valuable addition to scheme
teaching functions. Students could explore functions (i.e. just small
"programs") to include the ability to control RCX objects not just character
sets or lines on a screen. I tend to view functions/programs as a "brick"
with inputs, outputs, and processes.
--
Richard Clemens
Associate Professor
Computer Science Department
West Virginia Wesleyan College
Buckhannon, West Virginia 26201
clemens@wvwc.edu
304.473.8421
----- Original Message -----
From: Eric Lind <ejlind@brain.uccs.edu>
To: <lego-robotics@crynwr.com>
Sent: Tuesday, May 11, 1999 1:08 PM
Subject: Re: Scheme
> It strikes me that Scheme is largely an academic language. Granted, there • are
> a few Scheme devotees out there who worship the language, but they seem to • be
> all at MIT or Rice. I think they've even written modules for web • programming
> with Scheme, but I have to wonder what psychotropic drugs they were on • when
> they did it. Scheme, like most functional languages, is based on • functions.
> One doesn't store values in variables, you have a function that returns • the
> value, which is then piped into another function, etc. I have to say I • learned
> recursion really well from it (as there are no iterative constructs, all
> looping is done via recursion), but I wouldn't want to use it in daily • life. I
> don't think it's appropriate for the RCX (to bring this back to oblego), • as it
> is a pure interpreted language and the stack costs for it would be huge.
>
> In lugnet.robotics, Alex Wetmore writes:
> > From: Joel Shafer <joel@connect.net>
> > > Could you give a brief description of scheme? I've heard that it is a
> > > fairly high level language and I know that a compiler or interpreter • exists
> > > for it on linux.
> >
> > http://www.scheme.org/
> >
> > In my view Scheme is the most useful subset of lisp, designed to make a
> > small, elegant, functional language. This is compared to Common Lisp, • which
> > is kind of a superset of the various lisp-dialects, meant to contain
> > everything.
> >
> > Note: I am not a lisp-expert, I just used Scheme in one of my university
> > classes, and have played around with Common-lisp a little bit. I would
> > probably recommend playing around with PbForth on the RCX. Forth is a
> > lightweight, interpreted, stack-based language. It doesn't have lambda
> > functions (I don't think it does at least), but has a similar sort of
> > environment to most scheme systems (you can type directly into the
> > interpreter).
> >
> > alex
> >
> > --
> > Did you check the web site first?: http://www.crynwr.com/lego-robotics
> --
> Did you check the web site first?: http://www.crynwr.com/lego-robotics
--
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