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conjunctive type in polymorphic variants
-
Conglun Yao
- Nicolas Pouillard
- Olivier Andrieu
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Date: | 2008-10-09 (08:43) |
From: | Olivier Andrieu <oandrieu@n...> |
Subject: | Re: [Caml-list] conjunctive type in polymorphic variants |
Hi, On Thu, Oct 9, 2008 at 06:15, Conglun Yao <yaoconglun@gmail.com> wrote: > Sorry, I can't fully understand the source code, but it seems we can > only define a polymorphic variant with only one additional type > declaration, like > `A of int or `A of (int * int) > rather than `A of int * int That's correct. > It looks wired, as we can directly define > type t = [ `A of int * int | `B of string ] in toploop or a *.ml file. yes, that's because ocaml handle the "of int * int" a bit differently in regular and polymorphic variant declarations: - in the regular variant the * is a separator between constructor arguments (thus two arguments) - polymorphic variants only have one argument, so int * int is treated as a whole type expression and * is the "tupling" operator So yes, this looks wired in the ocaml parser. -- Olivier