scheme.rb

cons = lambda { |a, b|
  lambda { |m| m.call(a, b) }
}

car = lambda { |m| m.call(lambda { |a, _| a }) }
cdr = lambda { |m| m.call(lambda { |_, b| b }) }

# A list that only uses lambdas

list = cons.call(1, cons.call(2, cons.call(3, nil)))

p car.call(list)                                # => 1
p car.call(cdr.call(list))                      # => 2
p car.call(cdr.call(cdr.call(list)))            # => 3
p cdr.call(cdr.call(cdr.call(list)))            # => nil