what_is_a_list.ml

  type 'a list = Nil | Cons of 'a * 'a list;;
type 'a list = Nil | Cons of 'a * 'a list
#

  let l = Cons (1, Nil);;
val l : int list = Cons (1, Nil)
#

  let hd, tl = match l with Cons (hd, tl) -> hd, tl;;
Warning 8: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
Nil
val hd : int = 1
val tl : int list = Nil
#
  let hd, tl = match tl with Cons (hd, tl) -> hd, tl;;
Warning 8: this pattern-matching is not exhaustive.
Here is an example of a value that is not matched:
Nil
Exception: "Match_failure //toplevel//:37:13".
#