[Caml-list] Creating recursive values

[Caml-list] Creating recursive values

[Jonathan Roewen]

Hi,

The title might not be quite correct, but I don't really know how to
describe it. Anyways, I'm trying to create a value which references
another value that has to reference the original value.

let make_window origin bounds title =
	let (x,y) = origin
	and (w,h) = bounds in
	let window = GroupedGraphic (
		x, y, [
			InteractiveGraphic (
				[(Up,Graphic (Rectangle (0,0,w+8,h+8), control_brush, control_pen))],
				[(MouseDrag, on_drag)] (* Where trouble begins =( *)
			);
			Graphic (Rectangle (4,4,w,h), white_brush, control_pen);
		]
	)
	and on_drag () = match window with
	| GroupedGraphic (x,y,lst) -> GroupedGraphic (x+mouse.x,y+mouse.y,lst);
	redraw_gui () in
	window

I don't really want to have to deconstruct the window, and reconstruct
it again. I tried to make a start on that, and it was very messy.
There _has_ to be a better way to solve this recursive problem.

Regards,
Jonathan Roewen

Re: [Caml-list] Creating recursive values

[skaller]

On Mon, 2005-02-07 at 13:54, Jonathan Roewen wrote:

For functions, which 'on_drag()' is one of:

> 	let window = GroupedGraphic (
          let rec window = .
              ^^^
> 				[(MouseDrag, on_drag)] (* Where trouble begins =( *)

> 	and on_drag () = match window with

just add 'rec' keyword as shown.


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