[pypy-dev] pypy in python3?

Armin Rigo arigo at tunes.org
Sun Mar 2 16:41:15 CET 2014

Hi Martin,

On 2 March 2014 13:03, Martin Matusiak <numerodix at gmail.com> wrote:
> I'm wondering whether there are any plans to port pypy itself to
> python 3 at some point. And what the benefits of that might be (other
> than having a more recent host language). Is there anything in python
> 3 that would make it easier/harder for pypy?

Just to make it clear to readers: this is about the language in which
PyPy is implemented; this is not about the fact that PyPy itself
implements Python 2.7 and 3.2 (currently).

If we were starting today, then we could certainly use some small new
features, like the ability to decorate function arguments rather than
the whole function.  However, that's about it as far as advantages go.
 There are small disadvantages too, like the unicode-everywhere model;
you'd have to write byte strings explicitly everywhere in order to
implement Python 2, or almost any small language you want to play
with.  That's the main difference from Python 2, ignoring new things
in the stdlib which we cannot use from RPython anyway.

But we're not starting today, and we have a very large code base
already.  As far as I'm concerned, Python 2 works nicely, is going to
stay around for a long time, and is stable --- i.e. does not require
us to adapt our code base every 2 years when a new Python 3.x version
goes out (even if the required work is usually minimal, as far as our
experience goes, from 2.3 to 2.7).  For this reason I imagine that
PyPy is going to be Python 2 forever.  As it runs on PyPy itself, we
won't even require a working CPython 2.x to get started, athough I'm
sure these will also remain available forever.

A bientôt,


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