pycategory 0.1.2

Python implementation of the Scala standard library.

pycategory

Installation

pip install works for this library.

pip install pycategory

Usage

Here is an example of how to use the pycategory package:

curry

from pycategory import curry

@curry
def function(arg1: int, /, arg2: int, arg3: int = 3, *, arg4: int = 4) -> int:
    return arg1 + arg2 + arg3 + arg4

function2 = function        # (int) -> ((int) -> int)
function1 = function2(1)    # (int) -> int
result = function1(2)       # int

Pipeline

from pycategory import Pipeline, curry

def squared(value: int) -> int:
    return value**2

assert 42**2**2 == ~(Pipeline(42) >> squared >> squared)

@Pipeline
@curry
def cubed(arg1: int, arg2: int, arg3: int) -> int:
    return arg1 * arg2 * arg3

assert 42**3 == ~(cubed << 42 << 42 << 42)

Either

from pycategory import Either, EitherDo, Frame, Left, Right

class Error(Frame):
    ...

@Either.do
def context(value: int) -> EitherDo[Error, int]:
    one = yield from Left[Error, int](Error(unmask=("value",)))
    two = 2
    three = yield from Right[Error, int](3)
    return one + two + three

match context(42).pattern:
    case Left(value):
        print(f"Left case {value}")
    case Right(value):
        print(f"Right case {value}")

Option

from pycategory import VOID, Option, OptionDo, Some, Void

@Option.do
def context() -> OptionDo[int]:
    one = yield from VOID
    two = 2
    three = yield from Some[int](3)
    return one + two + three

match context().pattern:
    case Void():
        print("Void case")
    case Some(value):
        print(f"Some case {value}")

Try

from pycategory import Failure, Success, Try, TryDo

@Try.hold(unmask=("value",))
def hold_context(value: int, /) -> int:
    if not value:
        raise Exception("error")
    return value

@Try.do
def context() -> TryDo[int]:
    one = yield from hold_context(0)
    two = 2
    three = yield from Success[int](3)
    return one + two + three

match context().pattern:
    case Failure() as failure:
        print(f"Failure case {failure.exception}")
    case Success(value):
        print(f"Success case {value}")