https://youtu.be/7oV7hiAsVTI?t=1272 py version

sicp-cons-car-cdr.py

from enum import Enum, auto
from typing import Any, Callable


class msg(Enum):
    FIRST = auto()
    SECOND = auto()


def cons(x: Any, y: Any):
    def dispatch(m: msg):
        if m == msg.FIRST:
            return x
        elif m == msg.SECOND:
            return y
        else:
            raise Exception("Unknown message")

    return dispatch


def car(x: Callable[[msg], Any]):
    return x(msg.FIRST)


def cdr(x: Callable[[msg], Any]):
    return x(msg.SECOND)


print(car(cons(1, 2)))
print(cdr(cons(1, 2)))