asynchronous - Catch exception from async workflow run on different thread -

let failing = async {     failwith "foo" }  let test () =     try         async.start(failing)         | exn -> printf "caught" 

this code doesn't catch exception. how can start asynchronous workflow on separate thread , catch exception in main program?

as alternative start workflow task , use it's methods , properties instead. example task.result rethrow exception again works, , tried:

let test () =     try        async.startastask failing        |> fun t -> t.result    _ -> printfn "caught" 

run

> test ();; caught val : unit = () 

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on differnt thread

sorry - saw want on different thread - in case want use internal approach rch gave - use continuewith (although bit ugly):

open system.threading.tasks  let test () =     (async.startastask failing).continuewith(fun (t : task<_>) -> try t.result _ -> printfn "caught") 

run

> test ();; caught val : task = system.threading.tasks.task {asyncstate = null;                                              creationoptions = none;                                              exception = null;                                              id = 3;                                              iscanceled = false;                                              iscompleted = true;                                              isfaulted = false;                                              status = rantocompletion;} 

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without async.catch

also don't need async.catch:

let test () =     async {        try           do! failing        _ -> printfn "caught"     } |> async.start