https://twitter.com/sb_syzygy/status/1534390184233795584

field-by-protocol.py

from typing import Protocol

class Ring(Protocol):
    @staticmethod
    def zero() -> "Ring":
        ...

    @staticmethod
    def identity() -> "Ring":
        ...

    def add(self, other: "Ring") -> "Ring":
        ...

    def mul(self, other: "Ring") -> "Ring":
        ...

    def inverse_add(self) -> "Ring":
        ...


# Assume T is Ring.
class RequirementForRing(SomeUnitTestFramework):
    def zero_is_additive_unit():
        x = for_any_element(T)
        assert x == T.zero().add(x) and x == x.add(T.zero())

    ...

class NonZeroIsMultipricativeGroup(Protocol):
    @staticmethod
    def zero() -> "Ring":
        ...

    @staticmethod
    def identity() -> "MultipricativeGroup":
        ...

    def mul(self, other: "MultipricativeGroup") -> "MultipricativeGroup":
        ...

    def inverse_mul(self) -> "MultipricativeGroup":
        ...

# Assume T is NonZeroIsMultipricativeGroup.
class RequirementForNonZeroIsMultipricativeGroup(SomeUnitTestFramework):
    def any_non_zero_has_unique_multiplicative_inverse():
        x = for_any_element(T)
        if x == T.zero():
            should_raise(x.inverse_mul())
        else:
            assert T.identity() == x.inverse_mul().mul(x) and T.identity() == x.mul(x.inverse_mul())

    ...

class Field(Protocol, Ring, NonZeroIsMultipricativeGroup):
    pass