PEP 3107 and stronger typing (note: probably a newbie question)

John Nagle nagle at
Fri Jun 22 21:14:25 CEST 2007

Paul Boddie wrote:
> P.S. I agree with the sentiment that the annotations feature of Python
> 3000 seems like a lot of baggage. Aside from some benefits around
> writing C/C++/Java wrappers, it's the lowest common denominator type
> annotation dialect that dare not be known as such, resulting from a
> lack of consensus about what such a dialect should really do, haunted
> by a justified fear of restrictive side-effects imposed by a more
> ambitious dialect (eg. stuff you get in functional languages) on
> dynamically-typed code. I don't think the language should be modified
> in ways that only provide partial, speculative answers to certain
> problems when there's plenty of related activity going on elsewhere
> that's likely to provide more complete, proven answers to those
> problems.

     I agree.  It's a wierd addition to the language.  It looks like
a compromise between the "no declarations" position and the "make
the language strongly typed" position.  But it's so ill-defined that
it's not helpful, and worse than either extreme.  The whole
approach is antithetical to the "only one way to do it" concept.
This could lead to misery when different libraries use
incompatible type annotation systems, which is not going to be fun.

     Python made it this far without declarations, and programmers
seem to like that.  We need to get Python performance up, and
the ShedSkin/Psyco restrictions seem to be enough to allow that.
Type annotations don't seem to solve any problem that really needs
to be solved.

     The main advantage of strongly typed systems is that more errors
are detected at compile time.  You pay for this in additional language
baggage.  PEP 3107 adds the excess baggage without providing the benefit
of compile time checks.

				John Nagle

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