On Tue, Jun 17, 2003 at 02:03:35PM -0400, Ye Wu wrote:
> Could you please tell me why the following doesn't work?

Sure.

> type shape = Square of int * int * int
>        |Circle of float * float * float;;
> let area s =
>  match s with
>    Square (_, _, d) -> d * d
>   |Circle (_, _, r) -> 3.14 *. r *. r;;

It's because the area function is not well-typed.  If the area function is
operating on a Square it wants to return an int; if it's operating on a
Circle it wants to return a float.  It can only return one type.

Owen

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