let gen = \x. if x <= 0 then lift 0
                        else [| (output y) + $(this (x + -1)) |]
in let code = gen 2
   in let quadruple = \y. (eval(code) + eval(code))
      in quadruple 3 + quadruple 4 // prints 3,3,3,3, 4,4,4,4