From: "François Pottier" <francois.pottier@inria.fr>
To: caml-list@inria.fr
Subject: Re: [Caml-list] Another question on subsumption of polymorphic variants
Date: Fri, 13 Nov 2020 14:07:36 +0100 [thread overview]
Message-ID: <ad95e76b-8dfc-5ba0-0f26-7e020a4d5994@inria.fr> (raw)
In-Reply-To: <23c53e70-4045-6812-9767-1bb60f70465e@inria.fr>
Le 13/11/2020 à 13:55, François Pottier a écrit :
> Yet I would intuitively expect it to be accepted, because
> the type [< `A > `A ] seems to be a subtype of the type [> `A ].
Replying to my own question, I note that the type-checker seems to
recognize that this subsumption relation holds when I use an
explicit coercion:
# let f x = (x : [`A] :> [> `A ]);;
val f : [ `A ] -> [> `A ] = <fun>
but it does not recognize it when comparing one module signature
against another module signature.
--
François Pottier
francois.pottier@inria.fr
http://cambium.inria.fr/~fpottier/
prev parent reply other threads:[~2020-11-13 13:07 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 12:55 François Pottier
2020-11-13 13:07 ` François Pottier [this message]
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