[Vm-dev] Pypy-Squeak VM generation news

Michael Haupt mhaupt at gmail.com
Tue Oct 23 08:36:58 UTC 2007

Hi again,

On 10/23/07, Andreas Raab <andreas.raab at gmx.de> wrote:
> So how does RPython compare to Slang? Or Pepsi for that matter?

RPython is a full-fledged Python with some restrictions: for example,
lists may only contain elements of the same type. I quote from the DLS
paper on PyPy:

"This sublanguage is not restricted syntactically, but only in the way
it manipulates objects of different types. The restrictions are a
compromise between the expressivity and the need to statically infer
enough type information to generate efficient code. RPython still
supports exceptions, inheritance but limited to single inheritance
with some mix-in support, dynamic dispatch, to some extent keywords
arguments and varargs, first-class function and class values, limited
use of bound methods, runtime isinstance and type queries, but no
runtime reflection. Bindings in class and global namespaces are
assumed constant. RPython code can be run on a Python interpreter
without severe semantics mismatches."

That is quite unlike Slang, isn't it?

BTW I don't think that, should SqueeSquee be approached one day, there
will have to be some kind of RSqueak. If Pepsi is the target language
of a SqueeSquee "VMMaker", then the differences are not too large.



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