From: Christian RINDERKNECHT <rinderkn@hugo.int-evry.fr>
To: caml-list@inria.fr
Cc: Christian RINDERKNECHT <rinderkn@hugo.int-evry.fr>
Subject: [Q] Four micro-questions on objects and modules.
Date: Tue, 2 Nov 1999 14:09:52 +0100 [thread overview]
Message-ID: <19991102140952.A16438@jones.int-evry.fr> (raw)
Hello,
I have a few questions on objects and modules.
1) Assume I compile m.ml made of: class c = object end
and m.mli: class c : object end
Now:
Objective Caml version 2.02
# #load "m.cmo";;
# let f = fun (x : #M.c) -> x;;
val f : (#M.c as 'a) -> 'a = <fun>
OK. What strikes me is:
# let g = fun (x : M.c) -> x;;
val g : M.c -> M.c = <fun>
What is the difference between f and g? If the type of g is
equivalent to #M.c -> #M.c, then according to the manual (#-types)
there is a difference, isn'it?
Moreover, I tought "M.c" was not syntactically correct when "c"
is a class (hence the "#" symbol)...
2) What is the semantics of the syntactic productions
(http://caml.inria.fr/ocaml/htmlman/node6.5.html):
typexpr : typexpr # class-path
| ( typexpr {, typexpr}) # class-path
3) Would it be possible to allow the "include" feature in class
types?
4) With values one can equivalently write:
# let (h : unit -> unit) = fun x -> x;;
val h : unit -> unit = <fun>
or
# let h = ((fun x -> x) : unit -> unit);;
val h : unit -> unit = <fun>
I prefer the former when the function expression is big and I don't
want my eyes to read it only in order to find the type annotation
at the end.
For the same sake, I think it would be consistent and useful to
allow class types, module types to qualify directly the module
names and the class names:
# module (M : S) = struct (* lot of stuff here *) end;;
^
Not a Syntax error!
and
# class (x : ct) = object (* lot of stuff here *) end;;
^
Not a Syntax error!
...and the same for method and value instances.
Best regards,
--
Christian
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next reply other threads:[~1999-11-03 20:54 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
1999-11-02 13:09 Christian RINDERKNECHT [this message]
1999-11-03 21:40 ` Jerome Vouillon
1999-11-07 10:37 ` Christian RINDERKNECHT
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