map/filter/reduce/lambda opinions and background unscientific mini-survey

Mike Meyer mwm at
Mon Jul 4 02:10:35 CEST 2005

Steven D'Aprano <steve at> writes:
> I don't object to adding sum and product to the language. I don't object
> to adding zip. I don't object to list comps. Functional, er, functions
> are a good thing. We should have more of them, not less.

Yes, but where should they go? Adding functions in the standard
library is one thing. Adding builtins is another. Builtins make every
python process heavier. This may not matter on your desktop, but
Python gets used in embedded applications as well, and it does
there. Builtins also clutter the namespace. Nothing really wrong with
that, but it's unappealing.

I'd say that removing functions is a bad thing. On the other hand, I'd
say moving them from builtins to the standard library when Python has
functionality that covers most of the use cases for them is a good

The latter has occured for map, filter, and reduce. Lambda I'm not so
sure of, but it gets swept up with the same broom. Moving the first
three into a library module seems like a good idea. I'm not sure about
removing lambda. Removing map, filter and reduce remove most of my
use cases for it. But not all of them.

Mike Meyer <mwm at>
Independent WWW/Perforce/FreeBSD/Unix consultant, email for more information.

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