[Python-Dev] lambda (x, y): (original) (raw)

Greg Ewing greg.ewing at canterbury.ac.nz
Sat Jan 25 06:41:14 CET 2014

Brett Cannon wrote:

On Fri, Jan 24, 2014 at 10:50 AM, Ram Rachum <ram at rachum.com_ _<mailto:ram at 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.

-- Greg

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