[pypy-dev] Who's developing language interpreters in PyPy

Simon Burton simon at arrowtheory.com
Mon Apr 23 21:40:11 CEST 2007

On Mon, 23 Apr 2007 15:13:36 -0400
"Terry Reedy" <tjreedy at udel.edu> wrote:

> | Naturally PyPy wouldn't be able to use its magical optimization abilities 
> on those bits
> Many to most of 'those bits' have been heavily optimized already, which is 
> why to use them.
> Terry Jan Reedy

Yes, but how about this idea: that we would like to take vector expressions,
such as the sum of three arrays, X+Y+Z, and instead of creating a temporary array
to house X+Y (and then summing with Z), we sum the elements from all three arrays at once.

This kind of calculation is very typical in numpy/R, where temporary arrays are created, transversed
then destroyed alot, and the CPU cache overheats, and people become generally unhappy.

Last year I had a look at teaching the rtyper to understand numpy expressions (see pypy.rpython.numpy),
with the idea of heading in this more intelligent direction. This year i discovered the pypy JIT and
had a brain orgasm; it would be very interesting to use (+develop) the JIT towards these cache friendly
ideas also.

It really makes no sense to reimplement R, i think, UNLESS you can interface with the present R libraries.
The big strength of R is it's many many libraries for statistics etc. I don't think it's much of an
interesting language in and of itself.


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