catchFail
  <try>
  | push ((flip ($)) ((flip ($)) ((flip ($)) ((flip ($)) Pure . (cons . const 'd')) . ((.) . (cons . const 'c'))) . ((.) . ((.) . (cons . const 'b')))) . ((.) . ((.) . ((.) . (cons . const 'a')))))
  | read
  | lift ($)
  | read
  | lift ($)
  | read
  | lift ($)
  | read
  | lift ($)
  | popFail
  | ret
  <handler>
    loadInput
    fail