sicp-2.4.rb

def cons(x,y)
	->(m){ m.call(x, y) }
end

def car(z)
	z.call( ->(p, q) {p} )
end

def cdr(z)
	z.call( ->(p, q) {q} )
end

def list(head = nil, *tail)
	cons(head, list(*tail)) if head
end

x = cons "first", "second"

puts car x 
puts cdr x

y = cons "outer", x

puts car y
puts car cdr y
puts cdr cdr y

z = list(1, 2, 5, 42, "test", 6)

puts car cdr cdr cdr z