[pypy-dev] a faster Python not a primary goal of PyPy?

[Lenard Lindstrom]

On 26 Sep 2005 at 8:56, holger krekel wrote:

>  
> I believe the idea with a PyPy/JS Interpreter is more 
> interesting, at least from the PyPy perspective.  Btw, 
> being faster than current JS interpreters is probably 
> easier than being faster than CPython :-) 
> Such a JS-interpreter implementation could be 
> integrated with browsers allowing JS and Python 
> directly in the browser. 
> 
> That being said, it might actually be worthwhile to compile 
> RPython to Javascript which should be reasonably fast
> for small programs.  One possibility is to just create 
> flowgraphs from a python program and then transform the 
> flowgraph to javascript source code (without much 
> annotation).  
> 
> I guess only real experiments would shed more light. 
> 
Hello everyone. Python and prototypes is one area where I have some personal 
experience. 

How well RPython will translate to Javascript depends on how fully RPython 
supports new-style classes. Javascript objects have single inheritance only. So 
problems arise immediately for multiple inheritance. An object space is needed to 
implement new-style classes on top of Javascript prototypes. All python arithmetic 
operations, attribute accesses and method calls become Javascript function calls. 
This adds a level of indirection to an already slow interpreter.

Finally Javascript has no 'goto' statement. So a switch statement within a loop is 
needed to handle the spaghetti code produced by tranforming a flowgraph. How 
much different is this from an interpreter loop?

So a Python program compiled to Javascript is essentially a Python interpreter
that runs in Javascript. How worthwhile is this? Of course if RPython only supports
single inheritance and improvements to flowgraph transformation will recover
Python's statement structure then a closer translation may be possible.

Lenard Lindstrom
<len-l at telus.net>