What is the value of
(match '(- ?x ?x) '(- w 3)) ?

  • A: ((?x w))
  • B: true
  • C: false
  • D: null
  • E: ((?x 3) (?x w))

    Answer: D

    The pattern does not match the input, because to do so would require ?x to match both w and 3.

    The answer returned is null, which can be of the specified return type, Cons. (false is type boolean, so it would cause a compiler error.)

    Contents    Page-10    Prev    Next    Page+10    Index