Re: [Ocaml-lib-devel] Dllist skip negative arguments

[Brian H. <bh...@sp...>]

On Tue, 4 Oct 2005, Amit Dubey wrote:

> Looking at Dllist.skip, this looks like a bug. A better implementation of
> skip might be:
>
> let skip node idx =
> let rec loop idx n =
> if idx == 0 then
> n
> else if idx>0 then
> loop (idx -1) n.next
> else
> loop (idx + 1) n.prev
> in
> loop idx node
>
> (The current version doesn't use n.prev for negative arguments). If there
> are no complains, I'll make this change.

I'm wondering if it might not be better to split the two loops, to avoid 
taking repeated branchs:

let skip node idx =
 	let rec floop idx n =
 		if idx == 0 then
 			n
 		else
 			floop (idx-1) n.next
 	in
 	let rec bloop idx n =
 		if idx == 0 then
 			n
 		else
 			bloop (idx-1) n.prev
 	in
 	if idx == 0 then
 		n
 	else if idx > 0 then
 		floop (idx-1) n.next
 	else
 		bloop ((-idx)-1) n.prev
;;

Brian