From: "Hongbo Zhang (BLOOMBERG/ 731 LEX)" <hzhang295@bloomberg.net>
To: caml-list@inria.fr
Subject: [Caml-list] typing question: universal type variable in class type
Date: Fri, 24 Jun 2016 18:22:38 -0000 [thread overview]
Message-ID: <576D7A6E012D045A003906FD_0_112375@p057> (raw)
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Dear all,
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
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next reply other threads:[~2016-06-24 18:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-24 18:22 Hongbo Zhang (BLOOMBERG/ 731 LEX) [this message]
2016-06-24 18:55 ` Jeremy Yallop
2016-06-24 19:09 Hongbo Zhang (BLOOMBERG/ 731 LEX)
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