Typing system vs. Java

Michael Abbott michael at rcp.co.uk
Wed Aug 1 08:56:14 CEST 2001


Skip Montanaro <skip at pobox.com> wrote in
news:mailman.996593278.31833.python-list at python.org: 

> 
>     Michael> Well, it's interesting to look at the byte code
>     interpreter source and to consider just how much time and
>     effort is spent in working out what the types of operands
>     are and therefore which particular operation to invoke. 
>     You can't avoid that without static typing of some sort.
> 
> Not so fast, bucko. ;-)
> 
> The prototypical proof-by-existence is Self.  Check out
> 
>     http://www.sun.com/research/self/

Thanks for the reference; quite an intruiging looking language there.  I 
don't really see how this affects my point, though.  I can see a number of 
published papers on optimisation techniques, but most of them seem to be 
about working out a static type inference regime, anyway!

> 
> Also, who said you had to compile your code before running it?  Armin
> Rego has been working on something called Psyco (Python Specializing
> Compiler) that at runtime converts VM bytecodes into another --
> partially typed -- virtual machine based upon the types of the inputs
> it sees. 

Hmm.  Well, with the current interpreter cost, I'm sure there's plenty of 
head-room for small improvements.  

The only real reference I could find for Psyco is this:
    	http://mail.python.org/pipermail/python-dev/2001-June/015503.html
which seems recent enough to be definitive.  I'm afraid that a factor of 
two improvement on the existing byte code iterpreter doesn't seem very 
startling to me.





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