unladen swallow: python and llvm

bearophileHUGS at lycos.com bearophileHUGS at lycos.com
Sun Jun 7 16:35:33 EDT 2009

Luis M. González:
> it seems they intend to do "upfront
> compilation". How?

Unladen swallow developers want to try everything (but black magic and
necromancy) to increase the speed of Cpython. So they will try to
compile up-front if/where they can (for example most regular
expressions are known at compile time, so there's no need to compile
them at run time. I don't know if Cpython compiles them before running

What I like of Unladen swallow is that it's a very practical approach,
very different in style from ShedSkin and PyPy (and it's more
ambitious than Psyco). I also like Unladen swallow because they are
the few people that have the boldness to do something to increase the
performance of Python for real.
They have a set of reference benchmarks that are very real, not
synthetic at all, so for example they refuse to use Pystones and the

What I don't like of Unladen swallow is that integrating LLVM with the
CPython codebase looks like a not much probable thing. Another thing I
don't like is the name of such project, it's not easy to pronounce for
non-English speaking people.


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