> > Does anyone know of any empirical evidence for the value
> > of types?
> > Or is it a myth that we invented to rationalize the typing
> > needed to improve the compiler's performance?
>
>Peter Norvig's book "Paradigms of Artificial Intelligence Programming: Case
>Studies in Common Lisp", 1992, Morgan Kaufman Publishers Inc. comes out
>strongly in favour of type-declarations, citing a case on page 318 where
>various hints to the compiler give a 40x speedup, so I see no need to
>rationalize.

I do believe that types lead to better compiler output -- I agree, no 
need to rationalize that.  The "value" that I'm questioning is that 
types lead to more bug-free code, that types "catch errors at compile 
time."  That claim seems untested yet, and I'm not even sure where it 
came from.  Is it a rationalization, e.g., "Well, we have to have 
types to make the code better -- let's claim that it's good for the 
programmer to use types! Improves their thinking, let's say!"  Well, 
maybe...

Mark

--------------------------
Mark Guzdial : Georgia Tech : College of Computing : Atlanta, GA 30332-0280
(404) 894-5618 : Fax (404) 894-0673 : guzdial at cc.gatech.edu
http://www.cc.gatech.edu/gvu/people/Faculty/Mark.Guzdial.html