[Types-sig] Type inferencing

Paul Prescod paul@prescod.net
Tue, 14 Dec 1999 12:24:32 -0800

Guido van Rossum wrote:
> > From: Paul Prescod <paul@prescod.net>
> >
> > Point taken. I am only willing to do type inferencing up to a function
> > level. After my "ML Experience" I am not willing to do it globally.
> [example snipped]
> I'm disappointed.  Jim Hugunin did global analysis on the pystone.py
> module -- 250 lines containing 14 functions and one class with two
> methods.  (He may actually have left out the class, but I'm pretty
> sure he did everything else.)  He got a 1000x speedup, which I think
> should be a pretty good motivator for those interested in (OPT).

I think that we may be talking at cross purposes. I am trying to define
a formal, independently implementable specification for a type system
that Python users will understand and like. Some languages use global
type inferencing as a formally specified part of the type checker but my
impression is that users do not like the resulting languages.

Jim created an implementation of an excellent, intelligent optimizing
compiler. His work is as, or more, interesting than mine, but it is a
different problem he is trying to solve. (OPT) comes into the picture
because my work makes his much, much easier and more effective in many
cases. I am totally in favor of particular global type inferencing
implementations, but am not in favor of requiring global type inference
of every static type checker implementation nor of requiring
safety-conscious Python users to think in terms of global type

 Paul Prescod  - ISOGEN Consulting Engineer speaking for himself
Three things to be wary of: A new kid in his prime
A man who knows the answers, and code that runs first time