From: SerP <serp@stork.ru>
To: Caml-list@yquem.inria.fr,
caml-list-bounces <caml-list-bounces@yquem.inria.fr>
Subject: Polymorphic method and polymorphic type
Date: Mon, 17 Mar 2008 13:21:41 +0300 [thread overview]
Message-ID: <47DE4635.7050101@stork.ru> (raw)
Simple example. All functions are fake.
class getter = object method add_some p = p+1 end;;
type 'a get_mode = [ `Read | `Watch of (#getter as 'a)];;
let string_of_get_mode (gm: 'a get_mode) = match gm with `Read -> "Read"
| `Watch g -> let i = g#add_some 1 in ("Watch "^ (string_of_int i));;
class c = object method pgm : 'a. ('a get_mode) -> string =
string_of_get_mode end;;
--------------
This expression has type 'a. (#getter as 'a) get_mode -> string
but is here used with type 'b. (#getter as 'b) get_mode -> string
Type #getter as 'c = < add_some : int -> int; .. >
is not compatible with type 'c
====================
Please help. Is it my error? how should we do that the right way?
next reply other threads:[~2008-03-17 10:21 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-03-17 10:21 SerP [this message]
2008-03-17 12:26 ` [Caml-list] " SerP
2008-03-17 12:51 ` Jacques Garrigue
2008-03-17 12:37 ` Jacques Garrigue
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