Re: [Python-Dev] VM and Language summit info for those not at Pycon (and those that are!)

[Allison Randal]

On 03/12/2011 11:17 AM, Nick Coghlan wrote:

About this bit from the VM meeting notes:
  - original Python-on-Parrot ran into problems due to semantic
  mismatches between Perl 6 and Python - reached the limits of the
  degree of difference the Perl 6 toolchain was willing to tolerate)

Would you have any pointers to more info about that?


No, it was something Allison Randal said during the summit. I don't if
anything more detailed has been written about the topic anywhere else.


I haven't posted/written about it anywhere yet. Happy to answer any 
questions, probably off-list so as not to bore people here. :) If the 
questions are particularly insightful, I might convert it directly into 
a Q&A blog post.


Allison
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Re: [Python-Dev] VM and Language summit info for those not at Pycon (and those that are!)

[Allison Randal]

On 03/12/2011 05:13 PM, Glenn Linderman wrote:

On 3/12/2011 10:42 AM, Allison Randal wrote:

I might convert it directly into a Q&A blog post.


I'd like to see that, or a summary, posted here. As a Perl-to-Python
convertee, I'm curious about the problematic semantic differences.


The short summary is that the Parrot VM is a very good semantic fit for 
Python (AFAICT, a better fit than it is for Perl 6, though I haven't 
done the feature-by-feature comparison). But, the initial implementation 
of Pynie (Python-on-Parrot) used NQP for parsing Python syntax and 
compiling it down to Parrot's AST. NQP is a library of Perl 6 regexes 
plus a stripped-down version of Perl 6 syntax, roughly the same general 
idea as PyPy's RPython. As with any Turing-complete system, it is 
certainly possible to implement a Python parser in NQP, but it required 
some ugly hacks, and it got to the point that I just hated working on it.


To be fair, the failure wasn't entirely technological, the project was 
also slowed by my PhD work, and by my new very intense and very 
interesting job.


I'd like to see Python-on-Parrot implementation work proceed in a more 
naturally Pythonic way, possibly as an alternate backend for PyPy or as 
an alternate output from the CPython grammar. I have a couple of 
volunteers who I'll be mentoring in the coming months, so we'll see what 
grows out of it.


Allison
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