felis-catus 0.dev2

🐈 Felis Catus – functional bits for Python

🐈 Felis Catus

Felis Catus is your taxonomic nomenclature, an endothermic quadruped, carnivorous by nature; your visual, olfactory, and auditory senses contribute to your hunting skills and natural defenses. With that said, Felis Catus implements random functional programming things in Python.

Installation

Install from PyPI:

pip install felis-catus

Build and install from source:

pip install git+https://github.com/LeeeeT/felis

Examples

Currying and uncurrying functions with felis.currying:

from felis.currying import curry, uncurry


@curry
@curry
def curried(a: int, b: str, c: bool) -> None:
    pass


uncurried = uncurry(uncurry(curried))


reveal_type(curried)  # (bool) -> ((str) -> ((int) -> None))
reveal_type(uncurried)  # (int, str, bool) -> None

Safe error handling with felis.either:

from felis import either


safe_int = either.catch(ValueError)(int)


@either.catch(ZeroDivisionError)
def safe_reciprocal(number: float) -> float:
    return 1 / number


safe_reciprocal_of_str = either.compose(safe_reciprocal)(safe_int)


match safe_reciprocal_of_str(input("Enter a number: ")):
    case either.Left(error):
        print(f"Error: {error}")
    case either.Right(reciprocal):
        print(f"Reciprocal: {reciprocal}")

Managing IO (or any other lazy computations) with felis.lazy:

from felis import lazy
from felis.currying import uncurry

main = \
    uncurry(lazy.then)(lambda: print("What's your name?"),
    uncurry(lazy.bind)(input, lambda name:
    lambda: print(f"Hi, {name}!")
))

main()

Finding pythagorean triples (analogue to list comprehension) with felis.list:

from felis.currying import uncurry
from felis.list import bind, guard, identity, range, then

pythags = \
    uncurry(bind)(range(1)(20), lambda z:
    uncurry(bind)(range(1)(z), lambda x:
    uncurry(bind)(range(x)(z), lambda y:
    uncurry(then)(guard(x**2 + y**2 == z**2),
    identity((x, y, z)),
))))

print(pythags)
# [(3, 4, 5), (6, 8, 10), (5, 12, 13), (9, 12, 15), (8, 15, 17)]

Parsing a list of natural numbers from a string with felis.parser:

from felis.parser import bracket, digit, map, run, separated, some, text

natural = map(int)(map("".join)(some(digit)))

naturals_without_brackets = separated(text(", "))(natural)

naturals_with_brackets = bracket(text("["))(text("]"))(naturals_without_brackets)

string = "[12, 345, 6789]"

result = run(naturals_with_brackets)(string)

print(result)  # Some(value=[12, 345, 6789])

That's all monads, btw. 🐈