Tuple parameter unpacking in 3.x

[bearophileHUGS at lycos.com]

Martin Geisler:
>   ci.addCallback(lambda (ai, bi): ai * bi)
> or
>   map(lambda (i, s): (field(i + 1), s), enumerate(si))
> Rewriting these to
>   ci.addCallback(lambda abi: abi[0] * abi[1])
> and
>   map(lambda is: (field(is[0] + 1), is[1]), enumerate(si))
> makes the code much uglier! And slightly longer.

I agree a lot. I can show similar examples of my code with sort/sorted
that contain a lambda that de-structures sequences of 2 or 3 items, to
define a sorting key.

As I've stated in the past, I'd like to see more support of pattern
matching in Python, and not less. People coming from Mathematica,
Scala, OcaML, etc, know they can be useful, and Scala shows that
Python too may find some usages for that.

I think they have removed (part of, not fully) this Python feature
mostly to simplify the C implementation of CPython.

So far I think this removal, and not using {:} as empty array literal
are the only two mistakes done during the design of Python 3. If you
look at the really large number of design decisions taken during the
creation of Python 3 itself, I think this is an exceptionally good
result anyway.

Bye,
bearophile