Hi guys,

I've been wrecking my tiny brain over this for a few days and I finally have to surrender and ask for advice. What I'm trying to do is create a small function that will draw little glyphs in points clicked by the user. After each click I want to still remember all previously created points, because in the next step I want to perform some more operations on them.
So it pretty much boils down to a trivial List<T>.Add operation from the imperative world.
This is how close I managed to get on my own, but it obviously doesn't do the job:

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drawingArea.ButtonReleaseEvent.Add (fun e -> click((int)e.Event.X, (int)e.Event.Y))

let point (x, y) = new Cairo.Point(x, y)
let points = [] //this is bad - every call returns an empty list - no idea how to fix it though

let click (x, y) =
    let p = point (x, y)
    let rec addPoint p points = 
        match points with
        | [] -> [point]
        | h::t -> h::(addPoint p t);
    ()

let drawPoints (c:Context) =
    List.iter (fun p -> drawPoint(c, p)) points

Obviously, the problem here is getting the "points" list out. I thought I've had a few ideas how to do it but they have all turned out embarrassingly bad. I'll appreciate all help.

Full code here: [link:gist.github.com]

Cheers,
Piotr