How do I create a multi-level TreeView using F#? - f#

Question

I would like to display a directory structure using Gtk# widgets through F#, but I'm having a hard time figuring out how to translate TreeViews into F#. Say I had a directory structure that looks like this:
Directory1
SubDirectory1
SubDirectory2
SubSubDirectory1
SubDirectory3
Directory2
How would I show this tree structure with Gtk# widgets using F#?
EDIT:
gradbot's was the answer I was hoping for with a couple of exceptions. If you use ListStore, you loose the ability to expand levels, if you instead use :
let musicListStore = new Gtk.TreeStore([|typeof<String>; typeof<String>|])
you get a layout with expandable levels. Doing this, however, breaks the calls to AppendValues so you have to add some clues for the compiler to figure out which overloaded method to use:
musicListStore.AppendValues (iter, [|"Fannypack" ; "Nu Nu (Yeah Yeah) (double j and haze radio edit)"|])
Note that the columns are explicitly passed as an array.
Finally, you can nest levels even further by using the ListIter returned by Append Values
let iter = musicListStore.AppendValues ("Dance")
let subiter = musicListStore.AppendValues (iter, [|"Fannypack" ; "Nu Nu (Yeah Yeah) (double j and haze radio edit)"|])
musicListStore.AppendValues (subiter, [|"Some Dude"; "Some Song"|]) |> ignore

Answer 1

I'm not exactly sure what you're looking for but here is a translated example from their tutorials. It may help you get started. Image taken from tutorial site.
I think the key to a multi-level tree view is to append values to values, iter in this line musicListStore.AppendValues (iter, "Fannypack", "Nu Nu (Yeah Yeah) (double j and haze radio edit)") |> ignore
// you will need to add these references gtk-sharp, gtk-sharp, glib-sharp
// and set the projects running directory to
// C:\Program Files (x86)\GtkSharp\2.12\bin\
module SOQuestion
open Gtk
open System
let main() =
Gtk.Application.Init()
// Create a Window
let window = new Gtk.Window("TreeView Example")
window.SetSizeRequest(500, 200)
// Create our TreeView
let tree = new Gtk.TreeView()
// Add our tree to the window
window.Add(tree)
// Create a column for the artist name
let artistColumn = new Gtk.TreeViewColumn()
artistColumn.Title <- "Artist"
// Create the text cell that will display the artist name
let artistNameCell = new Gtk.CellRendererText()
// Add the cell to the column
artistColumn.PackStart(artistNameCell, true)
// Create a column for the song title
let songColumn = new Gtk.TreeViewColumn()
songColumn.Title <- "Song Title"
// Do the same for the song title column
let songTitleCell = new Gtk.CellRendererText()
songColumn.PackStart(songTitleCell, true)
// Add the columns to the TreeView
tree.AppendColumn(artistColumn) |> ignore
tree.AppendColumn(songColumn) |> ignore
// Tell the Cell Renderers which items in the model to display
artistColumn.AddAttribute(artistNameCell, "text", 0)
songColumn.AddAttribute(songTitleCell, "text", 1)
let musicListStore = new Gtk.ListStore([|typeof<String>; typeof<String>|])
let iter = musicListStore.AppendValues ("Dance")
musicListStore.AppendValues (iter, "Fannypack", "Nu Nu (Yeah Yeah) (double j and haze radio edit)") |> ignore
let iter = musicListStore.AppendValues ("Hip-hop")
musicListStore.AppendValues (iter, "Nelly", "Country Grammer") |> ignore
// Assign the model to the TreeView
tree.Model <- musicListStore
// Show the window and everything on it
window.ShowAll()
// add event handler so Gtk will exit
window.DeleteEvent.Add(fun _ -> Gtk.Application.Quit())
Gtk.Application.Run()
[<STAThread>]
main()