From: Jacques Garrigue <garrigue@kurims.kyoto-u.ac.jp>
To: BeckW@t-systems.com
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] strange behaviour with variants and "cannot be generalized"
Date: Tue, 09 Sep 2003 21:11:56 +0900 [thread overview]
Message-ID: <20030909211156G.garrigue@kurims.kyoto-u.ac.jp> (raw)
In-Reply-To: <ADD42C8394EBD4118A3D0003470C18F00950F3D6@G9JJT.mgb01.telekom.de>
From: "Beck01, Wolfgang" <BeckW@t-systems.com>
> v1.ml ----------------------------
>
> open Vtop
>
> type t = {
> v1_x : int array;
> }
>
> let init = `V1 { v1_x = [| 0 |] }
>
> compilation fails with "The type of this expression _[> `V1 of t ] Vtop.t,
> contains type variables that cannot be generalized"
>
> However, if I change the type of v1_x to a string or some large struct,
> it compiles without warning and works. The error seems only to occur
> with arrays. I am using version 3.06.
>
> Is there an explanation for this behaviour?
Sure: [| 0 |] creates a mutable data structure, and as such is
considered as a side-effecting expression. As a result the type of
init cannot be generalized.
OCaml 3.07 is more clever about that, and the above program would be
accepted with no problem.
Jacques Garrigue
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prev parent reply other threads:[~2003-09-09 12:11 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-09-09 7:15 Beck01, Wolfgang
2003-09-09 12:11 ` Jacques Garrigue [this message]
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