From: Louis Gesbert <louis.gesbert@laposte.net>
To: Jon Harrop <jon@ffconsultancy.com>
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] Bugs with pattern-matching and exceptions
Date: Wed, 01 Mar 2006 12:10:21 +0100 [thread overview]
Message-ID: <f64914aa6debca404f0f005cd2dcac42@myco.ath.cx> (raw)
In-Reply-To: <200602281333.52448.jon@ffconsultancy.com>
> Can you reproduce this failure of the type system in the top-level
> without using marshalling? I haven't been able to.
Yes, this was without marshalling: when you use an alias to an exception
which has been redefined afterwards, some type information seems to be lost
by the top-level.
# type t = X;;
type t = X
# exception E of t;;
exception E of t
# exception E' = E;;
exception E' of t
# E' X;;
- : exn = E X
# exception E of string;;
exception E of string
# E' X;;
- : exn = E 0
Here we alias E with E', then redefine E (no matter with what), and E'
shows its argument as int... However, this seems to be only a problem with
the toplevel pretty-printer, not a real type problem since I didn't manage
to make O'Caml accept badly typed expressions this way. This is with O'Caml
3.09.1.
I guess this is linked to the problems of equality and marshalling:
exceptions are non-standard variant types which confuse the run-time in
some dark corners.
next prev parent reply other threads:[~2006-03-01 11:10 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-02-28 12:29 Louis Gesbert
2006-02-28 15:51 ` [Caml-list] " Alain Frisch
2006-03-01 0:03 ` Jacques Garrigue
2006-03-01 7:00 ` Alain Frisch
[not found] ` <200602281333.52448.jon@ffconsultancy.com>
2006-03-01 11:10 ` Louis Gesbert [this message]
2006-03-01 23:07 Louis Gesbert
2006-03-02 6:47 ` Alain Frisch
2006-03-03 9:02 ` Louis Gesbert
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