On Mon, Sep 18, 2006 at 09:26:15PM -0400, Denis Bueno wrote:
> What is the reason that expression A won't compile? Can't one variable
> stand for a tuple in a pattern-matching clause?

somebody was discussing a similar issue on the beginners 
mailing list this week:

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 d -> d;; ;;
- : string * int = ("hi there", 4)

if you want to pattern match the tuple you need to add parenthesis 
in the type declaration.

have a look here for a detailed explanation:
http://www.archivesat.com/Ocaml_Beginners/thread1620469.htm

:)
p

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