Re: [Caml-list] Sorted list

[Philippe Wang <lists@philippewang.info>]

tmp123@menta.net wrote:
> Hello,
>
> In order to implement a timers subsystem, I need a module with the 
> following values:
>
> *) add_timer : time -> ( unit -> unit ) -> timerid,
> for public usage, where "add_timer t f" means execute "f" at time 
> "t".  The result is an identifier who allows cancelation of the timer.
> *) cancel_timer: timerid -> unit
> for public usage, cancel a previously added timer
> *) peek_minimum_timer : unit -> ( time, unit -> unit )
> for internal usage, get the timer with minimum time. Returns the time 
> and the related function.
> *) remove_minimum_timer : ?? -> unit
> for internal usage, remove the timer with the minimum time. It will be 
> called after execute a timer.
>
> Thus, in a generic sense, what I need is a "sorted list", with easy 
> insertion of elements, and peek/pop of the head (minimum).
>
> Of the standard modules, the most similar seems "set", because allows 
> insertion and has the funcion "min_elt". However, the problem is, if 
> two timers have the same time, addition of the second one removes the 
> first.
>
> Please, has someone any sugestion?
>
> Thanks a lot.
Hello,

Let's remind that Set.Make is a functor that takes a module with
sig
  type t
  val compare : t -> t -> int
end

If you simply give him a compare function that never returns 0, then you 
can add multiple elements that are the same.

Cheers,

--
Philippe Wang
  mail[at]philippewang.info