match.py

from dataclasses import dataclass
from typing import Any

@dataclass
class List:
	pass
	
@dataclass
class Empty(List):
	def __iter__(self):
		return
		yield
	
@dataclass
class Cons(List):
	head: Any
	tail: List
	
	def __iter__(self):
		yield self.head
		yield from self.tail

def newList():
	return Empty()

def isEmpty(l):
	match l:
		case Empty():
			return True
		case Cons():
			return False
	
def car(l):
	match l:
		case Cons(head, tail):
			return head
		case Empty():
			raise Error("car of empty list")
	
def cdr(l):
	match l:
		case Cons(head, tail):
			return tail
		case Empty():
			raise Error("cdr of empty list")
			
def showList(l):
	match l:
		case Cons(head, tail):
			return f"{head} -> {showList(tail)}"
		case Empty():
			return "ø"

l = newList()
l1 = Cons(15,Cons(12,Cons(2,l)))
v = car(l1)
l2 = cdr(l1)
l3 = Cons(4,Cons(5, l2))
print(showList(l))
print(showList(l1))
print(v)
print(showList(l2))
print(showList(l3))

object.py

from dataclasses import dataclass
from typing import Any

@dataclass
class List:
	pass
	
@dataclass
class Empty(List):
	def __iter__(self):
		return
		yield
		
	def isEmpty(self):
		return True
		
	def car(self):
		raise Error("car of empty list")
		
	def cdr(self):
		raise Error("cdr of empty list")
		
	def show(self):
		return "ø"
	
@dataclass
class Cons(List):
	head: Any
	tail: List
	
	def __iter__(self):
		yield self.head
		yield from self.tail
		
	def isEmpty(self):
		return False
		
	def car(self):
		return self.head
		
	def cdr(self):
		return self.tail
		
	def show(self):
		return f"{self.head} -> {self.tail.show()}"

def newList():
	return Empty()

l = newList()
l1 = Cons(15,Cons(12,Cons(2,l)))
v = l1.car()
l2 = l1.cdr()
l3 = Cons(4,Cons(5, l2))
print(l.show())
print(l1.show())
print(v)
print(l2.show())
print(l3.show())