Review of my Xamarin F# Event Code Leads To Improvements

Not at all surprisingly, it turns out that F# events need not be the crufty structures I showed in my previous post.

First, Xamarin‘s David Siegel suggested “Let the Event type be inferred, don’t define a delegate type, and send simple typed values rather than EventArgs:”


open System

type Control() =
let hello = Event<_>()

member this.Hello = hello.Publish
member this.Speak() = hello.Trigger "yo!"

let control = Control()

control.Hello.Add < | fun msg ->
printfn "Received '%s'" msg

control.Speak()

While Ryan Riley suggested a step further down the reactive line:

To remain consistent with your pipe forwards when using events, you can use the Observable module:
do myItem.FooEvent |> Observable.add (fun o args -> …)
or even
let disposable = myItem.FooEvent |> Observable.subscribe (fun o args -> …)
You can also expose an event as an IObservable rather than as an event if you like:
FooEvent.Publish :> IObservable


I also learned from @kemnet that List.choose id is the idiomatic way to transform a List<option> into a List of Some values.

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