.net - Async.fromBeginEnd with WinForms Begin/EndInvoke -

i'm trying write async wrapper on top of function called listcontrols extracts list of forms controls starting root control. plan implement in terms of control.begininvoke, control.endinvoke , async.frombeginend

the code below:

type private listcontrols = delegate of unit -> control list  let asynclistcontrols (root:forms.control) : async<control list> =      let begininvoke (_, _) =          new listcontrols(fun () -> listcontrols root)         |> root.begininvoke      let endinvoke result =          root.endinvoke result :?> control list      async.frombeginend (begininvoke, endinvoke) 

the behavior i'm getting endinvoke never executed. knows doing wrong? there better approach?

edit

just make clear, computation executed async.runsynchronously.

also if replace code

/// code below reproduced memory , might not compile let asynclistcontrols (root:forms.control) : async<control list> =      let ctx = windowsformssynchronizationcontext.current      async {          do! async.switchtocontext ctx          return listcontrols root          do! async.switchtothreadpool ()      } 

...then seems work don't because of forced context switches , fact async computation supposed built on ui thread

async different task in doesn't start on creation. daniel pointed out, must explicitly start async using async.runsynchronously or other method.