Pereira,
The only comment I have is that your dispatch function scans the list
twice (once for odds, once for evens) when it doesn't have to. For
example:
let dispatch xs =
let rec aux (odds,evens) xs =
match xs with
| [] -> odds, evens
| x :: [] -> x :: odds, evens
| x :: y :: zs -> aux (x :: odds, y :: evens) zs
in aux ([],[]) xs
Regards,
Chris
On Thu, Aug 28, 2008 at 8:21 AM, Pereira Lucien
<[EMAIL PROTECTED]> wrote:
>
> Hi,
>
> I'm interested in improve my skills concerning OCaml language. It
> should be nice to give me
> you opinion about this code. Is it optimal ? Do I respect functionnal
> programation style ?
> Do you have another implementation to propose ?
>
> Thanks
>
> (*
> * return an half list (odd positions)
> *)
> let rec oddElements list = match list with
> [] -> []
> | head::_::tail -> head::(oddElements tail)
> | head::[] -> head::[]
>
> (*
> * return an half list (even positions)
> *)
> let rec evenElements list = match list with
> [] -> []
> | _::a::tail -> a::(evenElements tail)
> | _::[] -> []
>
> (*
> * Split a list, returns a couple of half list
> *)
> let dispatch list = (oddElements list, evenElements list)
>
> (*
> * Merge two sorted list in order to return a sorted list too
> *)
> let rec merge (list1, list2) rel = match (list1, list2) with
> (hd1::tl1, hd2::tl2) ->
> begin if rel hd1 hd2 <= 0 then hd1::(merge (tl1, list2) rel)
> else hd2::(merge (list1, tl2) rel)
> end
> | ([], _) -> list2
> | _ -> list1
>
> (*
> * Ordinary relation function for integers
> *)
> let relInt a b = if (a < b) then -1 else
> begin if (a > b) then 1
> else 0
> end
>
> (*
> * The mergeSort itself, It works ! ;)
> *)
> let rec mergeSort list rel = match list with
> [] -> []
> | a::[] -> a::[]
> | _ -> let (a,b)=dispatch list in
> let c=mergeSort a rel in
> let d=mergeSort b rel in merge (c,d) rel
>
> >
>
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