impartial

impartial is a lightweight extension of functools.partial that allows modifying positional and keyword arguments in a functional style.

The main idea is that any function wrapped with impartial gets a method with_<keyword>(value) for every keyword argument of that function. Each with_<keyword>(value) method returns a new impartial function with that keyword being modified.

>>> from impartial import impartial
>>> @impartial
... def power(x, exponent):
...     return x ** exponent
...
>>> power
impartial(<function power at 0x10d54e790>)
>>> square = power.with_exponent(2) # behaves like functools.partial(square, exponent=2)
>>> square
impartial(<function power at 0x10d54e790>, exponent=2)
>>> square(3)
9

Features:

• the with_<keyword>(value) methods can be arbitrarily chained
• impartial functions are immutable: any "modification" of arguments returns a new impartial function
• very lightweight (~50 LOC and no dependencies)
• fully compatible with functools.partial (impartial is a subclass of functools.partial)
• can be used as a decorator

To install this package, run:

pip install impartial