fz 0.1.1

Quick and efficient lambda functions.

Quick and efficient lambda functions.

What is fz?

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.

Syntax

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.

Example Uses

Simple Arithmetic

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]

Attribute and Item Access

>>> 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]

Function Calls

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

Supported Operations

• Binary operators

• Unary operators

• Attribute access (some names are used for the implementation)

• Subscript (item access)

• iter

• next

• abs

License

fz is free software, licensed under the GNU General Public License, version 2. For more information see the LICENSE file.

Source

Source code is hosted on github at https://github.com/llllllllll/fz.