JS backend is translating restricted subset of Python called RPython.
This seems to be infeasible, since JS is truly a dynamic language,
that's why we removed it. The other reason why we removed it, is that
noone seems to be interested enough in maintaining it.

As far as I know pyjamas does not translate a subset of python, but
pythonized javascript - ie it does not preserve python features, but
rather tries to implement python syntax which is javascript at the


On Wed, Apr 22, 2009 at 6:45 AM, Luke Kenneth Casson Leighton
<l...@lkcl.net> wrote:
> hi,
> i was just checking http://wiki.python.org/moin/WebBrowserProgramming
> specifically the python-to-javascript compiler section and was
> surprised to find that the link to the "JS Using" tutorial no longer
> works.  on further investigation, it would appear that pypy have
> completely removed all mention of javascript as a back-end from the
> pypy documentation.  all tutorials are gone.  the demo "bnb" fails.
> as the lead developer of pyjamas, the python-to-javascript compiler,
> this leaves me slightly ... concerned, as it implies that pyjamas is
> now the sole and exclusive free software python compiler which can be
> used seriously by developers to create web applications.
> what seems to be the problem?
> is there a technical / language-translation issue that cannot be
> overcome? someone said (on the LLVM unladen/swallow list) that adding
> advanced features like metaclass support would be hard - this was
> proven to be incorrect, by writing an implementation of "type()" for
> pyjamas in under 24 hours and about 100 lines of javascript.  pyjamas
> is tiny by comparison (it uses the existing AST / Compiler module /
> translator) to pypy, so there is very little actually going on, which
> makes it that much easier to follow its example.  the main pyjs
> compiler is what... 1400 lines of python, and pyjslib.py which
> contains the majority of the builtins (dict, list, tuple, str) is a
> further 1400 lines.
> so - what seems to be the problem?
> or am i mistaken and the javascript back-end support is just in the
> process of being rewritten?
> l.
> _______________________________________________
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