Computers obviously not harmful (was: Re: [plt-scheme] Computers considered harmful)

From: John Clements (clements at
Date: Mon May 11 13:10:29 EDT 2009

On May 11, 2009, at 1:45 AM, Noel Welsh wrote:

> On Fri, May 8, 2009 at 8:07 PM, John Clements <clements at 
> > wrote:
>> To be somewhat more specific: imagine using an FRP model to program  
>> a robot
>> to add one to each element of a list:  The robot's state would  
>> probably
>> include 'what element I'm visiting', and perhaps an 'add one'  
>> operation.
>>  The point is that even a purely functional solution is placed into  
>> a robot
>> framework that turns it into a sequence of mutations.
> Depends upon the level of abstraction. Imagine a robot with a binary
> sensor pair? and two actions, head and rest...

Yes, I'm imagining it: the solution is still going to look imperative,  


(define (react state)
   (cond [(empty-sensor? state) (return counter)]
         [else (set counter (+ counter 1)) (move-to-cdr)]))

It appears to me that applying the "robot model" to introductory  
programming is not going to help you make the crucial bridge to  
algebraic programming.

> Are you firing shots across MIT's bow?
> [ 
> ]

Hardly.  I'm still in chatting-in-the-pub mode. I hadn't seen this,  
though, so: many thanks!


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