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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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Calibration of seismometers.

Data access via web services.

Cache rewrite.

Extending OpenSSH.

C-ORM: docs, API.

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Algebraic ABCs - A DSL for Types in Python

From: andrew cooke <andrew@...>

Date: Fri, 29 Apr 2011 22:28:21 -0300

This is a draft, and the pytyp library it describes is not the one available
for download (although it is in hg on Google code), but I wanted to put it out
there in case anyone had any comments (which would be MUCH appreciated)

I think it's pretty cool.  It's a DSL for Python that integrates with ABCs to
extend Python's types.  Some examples:

    >>> isinstance(5, Or(int, str))
    >>> isinstance("five", Or(int, str))

    >>> @checked
    ... def int_list_len(s:[int]) -> int:
    ...     return len(s)
    >>> int_list_len([1,2,3])
    >>> int_list_len('abc')
    Traceback (most recent call last):
    TypeError: Type Seq(int) inconsistent with 'abc'.

    >>> class Foo:
    ...     def __init__(self, x):
    ... 	self.x = x
    >>> ifoo = Foo(1)
    >>> sfoo = Foo('one')
    >>> assert isinstance(ifoo, Foo)
    >>> assert isinstance(sfoo, Cls(Foo))
    >>> assert isinstance(ifoo, And(Foo, Atr(x=int)))
    >>> assert not isinstance(sfoo, And(Foo, Atr(x=int)))

Anyway, the paper is at http://www.acooke.org/pytyp.pdf


PS If you are reading this post in the future (woot!  flying cars!) then I may
have replaced the link with a more up-to-date version, and updated the
library, of course.

Updated Python Types Draft

From: andrew cooke <andrew@...>

Date: Fri, 6 May 2011 21:49:18 -0300

I've just posted an updated draft of the Python Types paper to the same link

This has a bunch of (I hope) improvements:

  - It tries to avoid confusion by avoiding terms that sounds like
    previously-existing terms for ideas that are only vaguely related.

  - It is clearer about what it doesn't do (but still has some way to go).

  - I'm starting to add multimethods.

I'm hoping that the sections before (and excluding) Conclusions are now pretty
much final (except that I need to implement and document more control over
exceptions for back-tracking).


Maybe not Multimethods

From: andrew cooke <andrew@...>

Date: Fri, 6 May 2011 21:52:59 -0300

Ironically, as I read what I just posted, I notice that what I am calling
mutlimethods are not really *methods* of the types used in dispatch.  So I
will need to fix that too...


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