Re: [Ocaml-lib-devel] Lazy lists?

[Nicolas C. <war...@fr...>]

>   Anybody has any idea of some lazy lists implementation in Ocaml?

Well partition could be easily added to Enum
Something like :

val partition : ('a -> bool) -> 'a Enum.t -> 'a Enum.t * 'a Enum.t

The implementation itself is quite easy :

let partition f t =
    let mem_true = Queue.create() in
    let mem_false = Queue.create() in
    let next b () =
        try
            Queue.pop (if b then mem_true else mem_false)
        with
            Queue.Empty ->
                let rec loop() =
                    let x = t.next() in
                    if f x = b then x else begin
                        Queue.push x (if b then mem_false else mem_true);
                        loop();
                    end;
                in
                loop()
    in
    from (next true) , from (next false)

But I'm not sure we should add it to Enum module because it creates a
unwelcomed dependency on the Queue module.

Regards,
Nicolas Cannasse