koerce 0.0.9

Python Pattern Matching

Python Pattern Matching

Reusable pattern matching for Python, implemented in Cython. I originally developed this system for the Ibis Project in pure python, but it can be useful in many other contexts as well.

Examples

from koerce import match, NoMatch
from koerce.sugar import Namespace
from koerce.patterns import SomeOf, ListOf

assert match([1, 2, 3, SomeOf(int, at_least=1)], four) == four
assert match([1, 2, 3, SomeOf(int, at_least=1)], three) is NoMatch

assert match(int, 1) == 1
assert match(ListOf(int), [1, 2, 3]) == [1, 2, 3]

from dataclasses import dataclass
from koerce.sugar import match, Namespace, var
from koerce.patterns import pattern
from koerce.builder import builder

@dataclass
class A:
    x: int
    y: int

@dataclass
class B:
    x: int
    y: int
    z: float


p = Namespace(pattern, __name__)
d = Namespace(builder, __name__)

x = var("x")
y = var("y")

assert match(p.A(~x, ~y) >> d.B(x=x, y=1, z=y), A(1, 2)) == B(x=1, y=1, z=2)

More examples and a comprehensive readme are on the way.

Packages are not published to PyPI yet.

Python support follows https://numpy.org/neps/nep-0029-deprecation_policy.html