Re: [Caml-list] extend object type?

["Hongbo Zhang (BLOOMBERG/ 731 LEX)" <hzhang295@bloomberg.net>]

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The syntax is a bit too heavy.
Note that structual typing is a killer feature for FFI with JS libraries,
it would be awesome if we could add some sugar to make below happen
type t1 = < f : int > 
type t2 = < ..t1 ; g : bool>
Is it possible to make it happen? Thanks -- Hongbo

From: leo@lpw25.net At: 02/10/17 04:42:52
To: caml-list@inria.fr
Subject: Re: [Caml-list] extend object type?

    
You can't do it for object types directly, but you can do it for class types:
 

 
  class type t1 = object method f : int end
 

 
  class type t2 = object inherit t1 method g : bool end
 

 
Defining a class type also defines the corresponding object type, which means the above results in types called t1 and t2 that are equal to the ones you want.
 

 
This trick also lets you use #t2 to refer to the polymorphic type < f : int; g : bool; .. >. 

 
Regards,
 

 
Leo 

 
On Thu, 9 Feb 2017, at 11:15 PM, Steffen Smolka wrote:
 
Is there syntax to conveniently extend object types?
 
Concretely, for types
 

 
type t1 = < f : int >
 
type t2 = < f : int; g : bool >
 

 
I would like a syntax that allows me to define t2 in terms of t1.
 

 
Thanks!
 
-- Steffen


  

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