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Not that I know of. But you can use this general implementation. It assumes
you have Enum (from Batteries, and ExtLib before). The (~~) prefix operator
is "Obj.magic".
Peng
(* makes the cross product of the given array of enumerations *)
let crossproductM enums initcount =
let numenums = Array.length enums in
let clean = Array.map clone enums in
let initstate = enums in
let rec cpmk cur curcount =
let reseti i = cur.(i) <- clone clean.(i) in
let tick () =
let rec tick_aux place =
if place >= numenums then ()
else
let ple = cur.(place) in
ignore (get ple);
if is_empty ple then (
reseti place;
tick_aux (place + 1)
)
in tick_aux 0; decr curcount in
let get () = Array.init numenums (fun i -> Option.get (peek cur.(i))) in
let nx () = match !curcount with
| 0 -> raise No_more_elements
| 1 -> decr curcount; get ()
| x -> assert (x >= 0); let ans = get () in tick (); ans in
let ct () = !curcount in
let cl () = cpmk (Array.init numenums (fun i -> clone cur.(i)))
(ref !curcount) in
make nx ct cl
in
( if initcount == 0 then empty ()
else cpmk initstate (ref initcount) )
let crossproduct enums =
let copy = Array.copy enums in
let initcount = Array.fold_left (fun acc e -> count e * acc) 1 copy in
crossproductM copy initcount
let cross2 (t1:'a t) (t2:'b t) : ('a * 'b) t =
~~(crossproduct [|~~t1; ~~t2|])
let cross3 (t1:'a t) (t2:'b t) (t3:'c t) : ('a * 'b * 'c) t =
~~(crossproduct [|~~t1; ~~t2; ~~t3|])
On Thursday 30 July 2009 01:56:50 pm Ligia Nistor wrote:
> Hi,
>
> Is there an already implemented way of doing the Cartesian product of 2
> sets in OCaml? My sets are of type Set.Make(Types), where Types is a module
> I have defined.
>
> Thanks,
>
> Ligia
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