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From: Jacques Garrigue <garrigue@math.nagoya-u.ac.jp>
To: nr@eecs.harvard.edu
Cc: caml-list@inria.fr
Subject: Re: [Caml-list] type abbreviation for open polymorhic variants?
Date: Fri, 19 Aug 2005 06:45:46 +0900 (JST)	[thread overview]
Message-ID: <20050819.064546.126145582.garrigue@math.nagoya-u.ac.jp> (raw)
In-Reply-To: <20050818210343.D8E391EB0C3@labrador.eecs.harvard.edu>

From: nr@eecs.harvard.edu (Norman Ramsey)

> I wish to define an abbreviation for the following type:
> 
>          [> `Nil
>     	 | `Number   of float
>     	 | `String   of string
>     	 | `Function of func
>      	 | `Table    of table
>          ]
> 
> I am assuming that the underlying machinery involves something like
> row polymorphism, but I don't know how to name the 'row variable'.

You can write
type 'a t = 'a constraint 'a =
     [> `Nil
     | `Number   of float
     | `String   of string
     | `Function of func
     | `Table    of table ]

But it seems simpler to write

type t =
     [ `Nil
     | `Number   of float
     | `String   of string
     | `Function of func
     | `Table    of table ]

and use it as [< t] where needed.

Jacques Garrigue


      reply	other threads:[~2005-08-18 21:45 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-08-18 21:03 Norman Ramsey
2005-08-18 21:45 ` Jacques Garrigue [this message]

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