Quick and efficient lambda functions.
fz
provides a nicer way to define lambda functions for Python 3. The syntax is inspired by C++ std::bind
, Scala lambdas, and quicklambda for python.
fz
lambdas use placeholder objects to represent the arguments to the new lambda. The placeholders look like: _1
, _2
, ..., all the way to _255
(the maximum number of positional arguments to a function).
To create a lambda, just build up an expression using these placeholders where you want the arguments to go.
Many lambdas are just simple arithmetic. For example:
>>> from fz import _1
>>> f = _1 + 1
>>> f(1)
2
>>> f(3)
4
>>> (_1 * 2)(3)
6
>>> (_1 ** 2)(3)
9
>>> list(map(_1 ** 2, range(5)))
[0, 1, 4, 9, 16]
>>> from fz import _1
>>> _1[0]([1, 2])
1
>>> list(map(_1[1], [(0, 1), (2, 3), (4, 5)]))
[1, 3, 5]
>>> _1.imag(1j)
1.0
>>> list(map(_1.imag, (1j, 1 + 2j, 2 + 3j)))
[1, 2, 3]
Because we can only wrap things top-down, we must explicitly wrap a function to be defered.
>>> from fz import _f, _1, _2, _3
>>> def f(a, b):
... return a + b
>>> _f(f)(_1, _2)(1, 2)
3
>>> g = _f(f)(_1, -1)
>>> g(1)
0
>>> flip = _f(_1)(_3, _2)
>>> flip(print, 1, 2)
2 1
- Binary operators
- Unary operators
- Attribute access (some names are used for the implementation)
- Subscript (item access)
iter
next
abs
fz
is free software, licensed under the GNU General Public License, version 2. For more information see the LICENSE
file.
Source code is hosted on github at https://github.com/llllllllll/fz.