functional_notations, a utility abusing Python @ symbol for the greater good

Why are we doing this?

For someone familiar with Mathematica's notation, it is very hard to live without the prefix function notation:

F @ log @ [array...]

For details of prefix, intrafix, postfix notations and other goodies, take a look at this comprehensive Mathematica.stackexchange wiki: what-are-the-most-common-pitfalls-awaiting-new-users

Todo

• Write examples and glorify functional_notations's abusive usage

Done

Installation

pip install functional_notations

Usage

from functional_notations import _F, F

A = _F(lambda x: x)
try:
    print(1 @ A)
except NotImplementedError:
    print('left @ is not implemented by design')
A @= 1
print("A = ", A)


# Examples
@_F
def mul(x):
    return x * 2


def some_fn(a, b):
    a + b


A = F(lambda x: x)
A @= 1
print("A = ", A)

print(F)
print(F @ some_fn)
print(F @ 1)

mul @ [1]
mul @ 5

import numpy as np

# Applying a function to an array
_F(lambda x: 2 + x) @ np.array([0, 3, 2, 1])
# Alternatively
F @ (lambda x: [2 * _ for _ in x]) @ [3, 1, 2, 4]
# Or Alternatively
F(lambda *x: 2 * x) @ [3, 1, 2, 4]

add = lambda x: x + 1
pow = lambda x: x ** 3

print(F)
# function composition:
print(F @ add)
print(F @ mul)
print(F @ add @ 10)
# from the left to the right
print(F @ add @ mul @ 10)
# print((F @ add @ mul @ 10) + 1)

print(_F(add) @ 1)
F @ list @ (lambda x: [_ * 2 for _ in x]) @ [1, 2, 3, 4]
# Out[15]: [2, 4, 6, 8]

# This is currently not working
F @ list @ (lambda fn: map(fn, [1, 2, 3, 4])) @ (lambda x: x + 1)

# This works
print(F @ list @ (lambda xs: [x + 1 for x in xs]) @ [1, 2, 3, 4])

To Develop

git clone https://github.com/episodeyang/functional_notations.git
cd functional_notations
make dev

To test, run

make test

This make dev command should build the wheel and install it in your current python environment. Take a look at the ./Makefile for details.

To publish, first update the version number, then do:

make publish