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From: Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>
To: Ben Millwood <bmillwood@janestreet.com>
Cc: OCaML List Mailing <caml-list@inria.fr>
Subject: Re: [Caml-list] Can we have more flexible destructive type substitution?
Date: Fri, 24 Jul 2015 23:37:24 +0900	[thread overview]
Message-ID: <BE5AB67C-B4C6-4FFA-A2C5-54B2827B8368@math.nagoya-u.ac.jp> (raw)
In-Reply-To: <CA+MHO51FYs9xwQ-XJ6O86sUL7Xi3A5xKM8QEhN3a7Et6bYGJ4g@mail.gmail.com>

On 2015/07/24 23:25, Ben Millwood wrote:
> 
> Currently, for [sig ... end with type lhs := rhs] to be valid, rhs needs to be an application of a type constructor to the same type parameters as lhs.
> 
> I'd like to do, at a minimum, [sig ... end with type 'a t := 'a], but this is currently forbidden. Are there conceptual obstacles to permitting arbitrary type expressions on the RHS, or are they simply not implemented yet?

I think there is no problem in theory.
The reason it is not allowed currently is that substitution relies on the path substitution code, which allows only replacing a path by another path.
Would have to think about how much new code this would require to implement. It might not be that much in practice.

Jacques Garrigue


      reply	other threads:[~2015-07-24 14:37 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-24 14:25 Ben Millwood
2015-07-24 14:37 ` Jacques Garrigue [this message]

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