On Sat, Jan 25, 2014 at 12:41 AM, Greg Ewing <greg.ew...@canterbury.ac.nz>wrote:
> Brett Cannon wrote: > >> >> On Fri, Jan 24, 2014 at 10:50 AM, Ram Rachum <r...@rachum.com <mailto: >> r...@rachum.com>> wrote: >> >> lambda (x, y): whatever >> >> http://python.org/dev/peps/pep-3113/ >> > > Part of the rationale in that PEP is that argument unpacking > can always be replaced by an explicitly named argument and > an unpacking assignment. No mention is made of the fact that > you can't do this in a lambda, giving the impression that > lambdas are deemed second-class citizens that are not worth > consideration. > > The author was clearly aware of the issue, since a strategy > is suggested for translation of lambdas by 2to3: > > lambda (x, y): x + y --> lambda x_y: x_y[0] + x_y[1] > > That's a bit on the ugly side for human use, though. > An alternative would be > > lambda xy: (lambda x, y: x + y)(*xy) > > Whether that's any better is a matter of opinion. As the author of the PEP and I can say that `lambda (x, y): x + y` can just as easily be expressed as `lambda x, y: x + y` and then be called by using *args in the argument list. Anything that gets much fancier typically calls for a defined function instead of a lambda.
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