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Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

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Lepl parser for Python.

Colorless Green.

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SVG experiment.

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Data access via web services.

Cache rewrite.

Extending OpenSSH.

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© 2006-2013 Andrew Cooke (site) / post authors (content).

Recursive Generators and Backtracking Search (Python)

From: "andrew cooke" <andrew@...>

Date: Tue, 5 Aug 2008 22:04:02 -0400 (CLT)

Very interesting thread from the Python archives -
http://mail.python.org/pipermail/python-list/2005-October/348485.html

The test code referred to in the final email from Tim is available here:
http://www.koders.com/python/fid9B99238B5452E1EDA851459C2F4B5FD19ECBAD17.aspx?s=mdef%3Amd5

I need to sleep, but that looks very much worth reading.

Andrew

I Have to Agree

From: "andrew cooke" <andrew@...>

Date: Sun, 10 Aug 2008 16:34:31 -0400 (CLT)

Now that I've started trying to write a parser with generators I have to
agree with the first post linked to above - it really is anuisance that
you have explicitly "bounc" the results from a recursive invocation.

I have lots of code that looks like this:

def my_thing(args...):
    if (still_not_finished):
       yield result_at_this_level
       for further in my_thing(less_args):
           yield further

The point is that the last two lines are somewhat silly - it would be
nicer to have something like:

def my_thing(args...):
    if (still_not_finished):
       yield result_at_this_level
       my_thing(less_args)

or

def my_thing(args...):
    if (still_not_finished):
       yield result_at_this_level
       yield_all my_thing(less_args)

or similar

Andrew

Recursive Descent Parser

From: "andrew cooke" <andrew@...>

Date: Wed, 4 Feb 2009 07:09:16 -0300 (CLST)

If you're interested in this post you may also be interested in the
recursive descent parser I wrote a few months later, in Python.  It's
called LEPL and available from http://www.acooke.org/lepl

Andrew

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