Can one partially apply the second argument of a function that takes no keyword arguments?

Question

Take for example the python built in pow() function.

xs = [1,2,3,4,5,6,7,8]

from functools import partial

list(map(partial(pow,2),xs))

>&g         


        

Answer 1

As already said that's a limitation of functools.partial if the function you want to partial doesn't accept keyword arguments.

If you don't mind using an external library ¹ you could use iteration_utilities.partial which has a partial that supports placeholders:

>>> from iteration_utilities import partial
>>> square = partial(pow, partial._, 2)  # the partial._ attribute represents a placeholder
>>> list(map(square, xs))
[1, 4, 9, 16, 25, 36, 49, 64]

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¹ Disclaimer: I'm the author of the iteration_utilities library (installation instructions can be found in the documentation in case you're interested).