Is tuple unpacking incompatible with `map'?

[François Pinard]

Hi, friends.

Is it possible that tuple unpacking is not compatible with `map', or is
there something I do not understand properly?  Here is a transcript.  This is
with Python 1.5.2.

>>> def postsort(pair):
...	return pair[1]
... 
>>> map(postsort, [(1, 'un'), (2, 'deux'), (3, 'trois')])
['un', 'deux', 'trois']
>>> def postsort(key, item):
...	return item
... 
>>> map(postsort, [(1, 'un'), (2, 'deux'), (3, 'trois')])
Traceback (innermost last):
  File "<stdin>", line 1, in ?
TypeError: not enough arguments; expected 2, got 1
>>>

Maybe `map' is trying to protect me against errors I'm not doing?  I would
prefer to use tuple unpacking here, as it allows for cleaner writing.

-- 
François Pinard   http://www.iro.umontreal.ca/~pinard