From: Jeremy Yallop <yallop@gmail.com>
To: Pietro Abate <pietro.abate@inria.fr>
Cc: Caml List <caml-list@inria.fr>
Subject: Re: [Caml-list] small GADT problem
Date: Thu, 19 May 2016 11:13:12 +0100 [thread overview]
Message-ID: <CAAxsn=HBGyCHHH_9hTNS_cV0nN9ZuGw7e+oKtM7ny1v=ht+=hw@mail.gmail.com> (raw)
In-Reply-To: <20160519095135.GA18204@pps.univ-paris-diderot.fr>
On 19 May 2016 at 10:51, Pietro Abate <pietro.abate@inria.fr> wrote:
> I fail to understand why in this simple example below I get a warning.
> Why the type annotations are not enough to convince the compiler that
> the method vartoint cannot accept anything else then UID.a ?
>
> module UID = struct
>
> type a
> type b
> type c
The types 'a', 'b' and 'c' are abstract, so the type checker doesn't
know that they are not equal. If you give them representations, like
this
type a = A
type b = B
type c = C
then the fact that they are distinct will become visible to the type
checker and you'll no longer see the warning.
prev parent reply other threads:[~2016-05-19 10:13 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-19 9:51 Pietro Abate
2016-05-19 10:13 ` Jeremy Yallop [this message]
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