From: Jeremy Yallop <yallop@gmail.com>
To: Hongbo Zhang <hzhang295@bloomberg.net>
Cc: Caml List <caml-list@inria.fr>
Subject: Re: [Caml-list] typing question: universal type variable in class type
Date: Fri, 24 Jun 2016 19:55:55 +0100 [thread overview]
Message-ID: <CAAxsn=EKMzp_jax9oFVL+z3xqe5vF6_kWh+ikMyoneXOrYX-uA@mail.gmail.com> (raw)
In-Reply-To: <576D7A6E012D045A003906FD_0_112375@p057>
On 24 June 2016 at 19:22, Hongbo Zhang (BLOOMBERG/ 731 LEX)
<hzhang295@bloomberg.net> wrote:
> When we wrote bindings for promise, we want to express things (simplified )
> like below:
>
> class type ['b] promise = object
> method then_ : 'a . ('b -> 'a promise) -> 'a promise
> end
>
> It is not expressible in OCaml, The universal type variable 'a can not be
> generalized, I tried this too:
>
> type 'b promise = < then_ : 'a . ('b -> 'a u) -> 'a u >
>
> It does not work either, thanks -- Hongbo
You might find something useful in this thread:
https://sympa.inria.fr/sympa/arc/caml-list/2015-10/msg00130.html
next prev parent reply other threads:[~2016-06-24 18:56 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-24 18:22 Hongbo Zhang (BLOOMBERG/ 731 LEX)
2016-06-24 18:55 ` Jeremy Yallop [this message]
2016-06-24 19:09 Hongbo Zhang (BLOOMBERG/ 731 LEX)
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