Elmish_WPF_core.fsx

#r "WindowsBase"
#r "PresentationCore"
#r "PresentationFramework"

open System.Windows
open System.Windows.Controls


type Action =
  | Increment
  | Decrement

let incButton = Button(Content="+")
let decButton = Button(Content="-")
let label = Label(Content="Hello")
let model = 0
let view model =
  label.Content <- sprintf "%d" model

let update (model : int32) (action : Action) =
  match action with
    | Increment -> model + 1
    | Decrement -> model - 1

let increment = Control.Observable.map (fun _ -> Increment) incButton.Click
let decrement = Control.Observable.map (fun _ -> Decrement) decButton.Click
let actions = Control.Observable.merge increment decrement
let stateObservable = Control.Observable.scan update model actions
Control.Observable.subscribe view stateObservable

let layout = StackPanel()
layout.Children.Add label
layout.Children.Add incButton
layout.Children.Add decButton

let window = 
  Window(
    Content = layout,
    Visibility = Visibility.Visible)

let app = Application(MainWindow = window)
app.Run()