Re: [Caml-list] OO programming

[Keiko Nakata <keiko@kurims.kyoto-u.ac.jp>]

> I have three wishes related to the case when a functor accepts a 
> structure that contains a single type or a single value:
> 
> 1) To be able to write
> 
>    module F(type t) = struct ...t... end
> 
> instead of
> 
>    module F(T : sig type t end) = struct ... T.t  ... end
> 
> and to write
> 
>    F(s)
> 
> instead of
> 
>    F(struct type t = s end)
> 
> 2) Similarly for values, to be able to write
> 
>    module F(val x : t) = struct ... x ... end
> 
> instead of
> 
>    module F(T : sig val x : t end) = struct ... T.x ... end
> 
> 3) Similarly for signatures:
> 
>    module type F = functor type t -> sig ... end
> 
>    module type F = functor val x : t -> sig ... end
> 
> I believe these are campl4 trivialities. There may be some hoxus-pocus 
> related to generating suitable names for T's above.

This is merely my personal preference, but I usually do not prefer 
implicit construction of names; for instance I may well get confused
by type error messages. 

Besides in this scenario:

>    module F(type t) = struct ...t... end

we need to decide which take precedence if the structure declares 
a type component named t. 

On the other hand, since the functor parameter 
has the role of the super class in the functor&fix-point approach 
to OO-style programming, it may well be useful 
to have an implicit way to refer to components of the parameter, 
as you proposed. Yet this may be confusing again if we consider 
multi-parameter functors a la multiple inheritance. 

What do you think?

With best regards,
Keiko