Date: Mon, 22 Feb 1999 11:44:32 +0300 (MSK)
From: Anton Moscal <msk@post.tepkom.ru>
To: Xavier Leroy <Xavier.Leroy@inria.fr>
Subject: Re: anonymous record types in variants
In-Reply-To: <19990217103259.47130@pauillac.inria.fr>
On Wed, 17 Feb 1999, Xavier Leroy wrote:
> It could be implemented this way. However, if you declare the
> datatype as
>
> type foo = A of {lbl1 : int; lbl2 : int}
>
> you would be forced to pattern-match it as follows
>
> match x with A{lbl1 = x; lbl2 = y} -> ...
>
> but you can't get access to the record itself and use the dot notation
> on it, as in
>
> match x with A r -> ... r.x ... r.y ...
But why? Natural semantic for anonymous types is the following: each
anonymous record or algebraic types declaration introduces new type
declaration in the current scope with some temporary type name. I.e.
type ('a, 'b) foo = A of 'a * {l : 'b; l2: int}
is a shortcut for:
type ('a, 'b) temp_name = {l1 : 'b; l2: int}
and ('a, 'b) foo = A of 'a * ('a, 'b) temp_name
Regards,
Anton Moscal
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