crisp.cr

record Cell, car, cdr

alias List = Nil | (-> Cell)

def inf(x = 0)
  inf :: -> Cell
  inf = -> { Cell.new(x, inf) }
end

def nat(x = 0)
  ->{ Cell.new(x, nat(x+1) as List) }
end

def cons(list, x)
  ->{ Cell.new(x, list) }
end

def car(list)
  list.try &.call.car
end

def cdr(list)
  list.try &.call.cdr
end


list = nat
10.times do
  puts car(list)
  list = cdr(list)
end

list = nil
ARGV.each do |x|
  list = cons list, x
end

puts "==="

while list
  puts car(list)
  list = cdr(list)
end