* [Caml-list] modules and objects
@ 2002-11-28 18:14 Vincent Poirriez
0 siblings, 0 replies; only message in thread
From: Vincent Poirriez @ 2002-11-28 18:14 UTC (permalink / raw)
To: caml-list; +Cc: dorian.petit
Hello list,
My non-important question is "why a module is not a first class
value? while objects are."
I was playing with modules and objects, and I found funny that it's
possible to simulate the constructor new, just by using a functor
taking an empty module.
module Void = struct end
module type Unit = sig end
module Build(M:Unit) = struct
let r = ref 0
let get () = !r
let put i = r :=i
end
module type CONS = sig val get: unit -> int end
module type PROD = sig val put: int -> unit end
module Foo = Build(Void)
module Bar = Build(Void)
module FooC= (Foo:CONS)
module FooP= (Foo:PROD)
What remains impossible is:
let lm = [FooP;FooC] impossible
While with objects:
class build = object
val mutable r = 0
method get = r
method put i = r <- i
end
let foo = new build
let bar = new build
class virtual cons = object
method virtual get : int
end
class virtual prod = object
method virtual put : int -> unit
end
let fooc = (foo :> cons)
let foop = (foo :> prod)
let lo = [foo;bar]
Is correct.
Vincent
--
courriel: vincent.poirriez@univ-valenciennes.fr
tel: (33)[0]3 27 51 19 53
Université de Valenciennes et du Hainaut-Cambrésis - Le Mont Houy
F-59313 Valenciennes cedex 9 - FRANCE
http://www.univ-valenciennes.fr/LAMIH/ROI/poirriez
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