The following is not intuitive to me.

# type 'a withint = Withint of 'a * int;;
type 'a withint = Withint of 'a * int
# let foo = Withint ("hi there", 4);;
val foo : string withint = Withint ("hi there", 4)
# match foo with Withint _ -> ();;
- : unit = ()
# match foo with Withint d -> d;; (* expression A*)
Characters 15-24:
  match foo with Withint d -> d;;
                 ^^^^^^^^^
The constructor Withint expects 2 argument(s),
but is here applied to 1 argument(s)
#

What is the reason that expression A won't compile? Can't one variable
stand for a tuple in a pattern-matching clause?

-Denis