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open System
open System.Threading

open System
open System.Threading

type private ComputationState<'a> =
    | NotStarted
    | Started
    | Completed of 'a

/// Allows to expose a F# async value in a C#-friendly API with the
/// semantics of Lazy<> (compute on demand and guarantee only one computation)
type LazyAsync<'a>(asyncValue:Async<'a>) = 

    let state = ref NotStarted
    let completed = Event<_>()
    let icompleted = completed.Publish

    member private __.doWhenCompleted f startIfNotRunning =   
        let continuation =      
            lock state <| fun () -> 
                match !state with
                | Completed value ->
                    Some <| fun () -> f value
                | Started ->
                    icompleted.Add f
                    None
                | NotStarted ->
                    icompleted.Add f
                    if startIfNotRunning then
                        state := Started
                        Some <| fun () ->
                            async {
                                try
                                    let! value = asyncValue
                                    lock state <| fun () -> state := Completed value
                                    completed.Trigger value
                                with _ -> ()
                            } |> Async.Start
                    else
                        None
        match continuation with
        | Some continuation -> continuation()
        | _ -> ()

    static member map f (x:LazyAsync<'a>) =
        LazyAsync(async { 
            let ev = Event<_>()
            x.GetValueAsync(fun value -> ev.Trigger value)
            let! value = Async.AwaitEvent(ev.Publish)
            return f value 
        }) 

    member x.Then f = 
        x.doWhenCompleted f false
        x

    /// Will start calculation if not started
    /// callBack will be called on the same thread that called GetValueAsync
    member x.GetValueAsync(callBack:Action<'a>) = 

        let synchronizationContext = SynchronizationContext.Current

        let doInOriginalThread f arg = 
            if synchronizationContext <> null then
                synchronizationContext.Post ((fun _ -> f arg), null)
            else
                f arg

        x.doWhenCompleted (doInOriginalThread callBack.Invoke) true

namespace System

namespace System.Threading

type private ComputationState<'a> =
  | NotStarted
  | Started
  | Completed of 'a

Full name: Script.ComputationState<_>

union case ComputationState.NotStarted: ComputationState<'a>

union case ComputationState.Started: ComputationState<'a>

union case ComputationState.Completed: 'a -> ComputationState<'a>

Multiple items
type LazyAsync<'a> =
  new : asyncValue:Async<'a> -> LazyAsync<'a>
  member GetValueAsync : callBack:Action<'a> -> unit
  member Then : f:('a -> unit) -> LazyAsync<'a>
  member private doWhenCompleted : f:('a -> unit) -> startIfNotRunning:bool -> unit
  static member map : f:('a -> 'a0) -> x:LazyAsync<'a> -> LazyAsync<'a0>

Full name: Script.LazyAsync<_>


 Allows to expose a F# async value in a C#-friendly API with the
 semantics of Lazy<> (compute on demand and guarantee only one computation)

--------------------
new : asyncValue:Async<'a> -> LazyAsync<'a>

val asyncValue : Async<'a>

Multiple items
type Async
static member AsBeginEnd : computation:('Arg -> Async<'T>) -> ('Arg * AsyncCallback * obj -> IAsyncResult) * (IAsyncResult -> 'T) * (IAsyncResult -> unit)
static member AwaitEvent : event:IEvent<'Del,'T> * ?cancelAction:(unit -> unit) -> Async<'T> (requires delegate and 'Del :> Delegate)
static member AwaitIAsyncResult : iar:IAsyncResult * ?millisecondsTimeout:int -> Async<bool>
static member AwaitTask : task:Task<'T> -> Async<'T>
static member AwaitWaitHandle : waitHandle:WaitHandle * ?millisecondsTimeout:int -> Async<bool>
static member CancelDefaultToken : unit -> unit
static member Catch : computation:Async<'T> -> Async<Choice<'T,exn>>
static member FromBeginEnd : beginAction:(AsyncCallback * obj -> IAsyncResult) * endAction:(IAsyncResult -> 'T) * ?cancelAction:(unit -> unit) -> Async<'T>
static member FromBeginEnd : arg:'Arg1 * beginAction:('Arg1 * AsyncCallback * obj -> IAsyncResult) * endAction:(IAsyncResult -> 'T) * ?cancelAction:(unit -> unit) -> Async<'T>
static member FromBeginEnd : arg1:'Arg1 * arg2:'Arg2 * beginAction:('Arg1 * 'Arg2 * AsyncCallback * obj -> IAsyncResult) * endAction:(IAsyncResult -> 'T) * ?cancelAction:(unit -> unit) -> Async<'T>
static member FromBeginEnd : arg1:'Arg1 * arg2:'Arg2 * arg3:'Arg3 * beginAction:('Arg1 * 'Arg2 * 'Arg3 * AsyncCallback * obj -> IAsyncResult) * endAction:(IAsyncResult -> 'T) * ?cancelAction:(unit -> unit) -> Async<'T>
static member FromContinuations : callback:(('T -> unit) * (exn -> unit) * (OperationCanceledException -> unit) -> unit) -> Async<'T>
static member Ignore : computation:Async<'T> -> Async<unit>
static member OnCancel : interruption:(unit -> unit) -> Async<IDisposable>
static member Parallel : computations:seq<Async<'T>> -> Async<'T []>
static member RunSynchronously : computation:Async<'T> * ?timeout:int * ?cancellationToken:CancellationToken -> 'T
static member Sleep : millisecondsDueTime:int -> Async<unit>
static member Start : computation:Async<unit> * ?cancellationToken:CancellationToken -> unit
static member StartAsTask : computation:Async<'T> * ?taskCreationOptions:TaskCreationOptions * ?cancellationToken:CancellationToken -> Task<'T>
static member StartChild : computation:Async<'T> * ?millisecondsTimeout:int -> Async<Async<'T>>
static member StartChildAsTask : computation:Async<'T> * ?taskCreationOptions:TaskCreationOptions -> Async<Task<'T>>
static member StartImmediate : computation:Async<unit> * ?cancellationToken:CancellationToken -> unit
static member StartWithContinuations : computation:Async<'T> * continuation:('T -> unit) * exceptionContinuation:(exn -> unit) * cancellationContinuation:(OperationCanceledException -> unit) * ?cancellationToken:CancellationToken -> unit
static member SwitchToContext : syncContext:SynchronizationContext -> Async<unit>
static member SwitchToNewThread : unit -> Async<unit>
static member SwitchToThreadPool : unit -> Async<unit>
static member TryCancelled : computation:Async<'T> * compensation:(OperationCanceledException -> unit) -> Async<'T>
static member CancellationToken : Async<CancellationToken>
static member DefaultCancellationToken : CancellationToken

Full name: Microsoft.FSharp.Control.Async

--------------------
type Async<'T>

Full name: Microsoft.FSharp.Control.Async<_>

val state : ComputationState<'a> ref

Multiple items
val ref : value:'T -> 'T ref

Full name: Microsoft.FSharp.Core.Operators.ref

--------------------
type 'T ref = Ref<'T>

Full name: Microsoft.FSharp.Core.ref<_>

val completed : Event<'a>

Multiple items
module Event

from Microsoft.FSharp.Control

--------------------
type Event<'T> =
  new : unit -> Event<'T>
  member Trigger : arg:'T -> unit
  member Publish : IEvent<'T>

Full name: Microsoft.FSharp.Control.Event<_>

--------------------
type Event<'Delegate,'Args (requires delegate and 'Delegate :> Delegate)> =
  new : unit -> Event<'Delegate,'Args>
  member Trigger : sender:obj * args:'Args -> unit
  member Publish : IEvent<'Delegate,'Args>

Full name: Microsoft.FSharp.Control.Event<_,_>

--------------------
new : unit -> Event<'T>

--------------------
new : unit -> Event<'Delegate,'Args>

val icompleted : IEvent<'a>

property Event.Publish: IEvent<'a>

member private LazyAsync.doWhenCompleted : f:('a -> unit) -> startIfNotRunning:bool -> unit

Full name: Script.LazyAsync`1.doWhenCompleted

val f : ('a -> unit)

val startIfNotRunning : bool

val continuation : (unit -> unit) option

val lock : lockObject:'Lock -> action:(unit -> 'T) -> 'T (requires reference type)

Full name: Microsoft.FSharp.Core.Operators.lock

val value : 'a

union case Option.Some: Value: 'T -> Option<'T>

member IObservable.Add : callback:('T -> unit) -> unit

union case Option.None: Option<'T>

val async : AsyncBuilder

Full name: Microsoft.FSharp.Core.ExtraTopLevelOperators.async

member Event.Trigger : arg:'T -> unit

static member Async.Start : computation:Async<unit> * ?cancellationToken:CancellationToken -> unit

val continuation : (unit -> unit)

static member LazyAsync.map : f:('a -> 'a0) -> x:LazyAsync<'a> -> LazyAsync<'a0>

Full name: Script.LazyAsync`1.map

val f : ('a -> 'a0)

val x : LazyAsync<'a>

val ev : Event<'a>

member LazyAsync.GetValueAsync : callBack:Action<'a> -> unit


 Will start calculation if not started
 callBack will be called on the same thread that called GetValueAsync

static member Async.AwaitEvent : event:IEvent<'Del,'T> * ?cancelAction:(unit -> unit) -> Async<'T> (requires delegate and 'Del :> Delegate)

member LazyAsync.Then : f:('a -> unit) -> LazyAsync<'a>

Full name: Script.LazyAsync`1.Then

member private LazyAsync.doWhenCompleted : f:('a -> unit) -> startIfNotRunning:bool -> unit

member LazyAsync.GetValueAsync : callBack:Action<'a> -> unit

Full name: Script.LazyAsync`1.GetValueAsync


 Will start calculation if not started
 callBack will be called on the same thread that called GetValueAsync

val callBack : Action<'a>

Multiple items
type Action =
  delegate of unit -> unit

Full name: System.Action

--------------------
type Action<'T> =
  delegate of 'T -> unit

Full name: System.Action<_>

--------------------
type Action<'T1,'T2> =
  delegate of 'T1 * 'T2 -> unit

Full name: System.Action<_,_>

--------------------
type Action<'T1,'T2,'T3> =
  delegate of 'T1 * 'T2 * 'T3 -> unit

Full name: System.Action<_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 -> unit

Full name: System.Action<_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 -> unit

Full name: System.Action<_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 -> unit

Full name: System.Action<_,_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6,'T7> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 * 'T7 -> unit

Full name: System.Action<_,_,_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6,'T7,'T8> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 * 'T7 * 'T8 -> unit

Full name: System.Action<_,_,_,_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6,'T7,'T8,'T9> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 * 'T7 * 'T8 * 'T9 -> unit

Full name: System.Action<_,_,_,_,_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6,'T7,'T8,'T9,'T10> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 * 'T7 * 'T8 * 'T9 * 'T10 -> unit

Full name: System.Action<_,_,_,_,_,_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6,'T7,'T8,'T9,'T10,'T11> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 * 'T7 * 'T8 * 'T9 * 'T10 * 'T11 -> unit

Full name: System.Action<_,_,_,_,_,_,_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6,'T7,'T8,'T9,'T10,'T11,'T12> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 * 'T7 * 'T8 * 'T9 * 'T10 * 'T11 * 'T12 -> unit

Full name: System.Action<_,_,_,_,_,_,_,_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6,'T7,'T8,'T9,'T10,'T11,'T12,'T13> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 * 'T7 * 'T8 * 'T9 * 'T10 * 'T11 * 'T12 * 'T13 -> unit

Full name: System.Action<_,_,_,_,_,_,_,_,_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6,'T7,'T8,'T9,'T10,'T11,'T12,'T13,'T14> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 * 'T7 * 'T8 * 'T9 * 'T10 * 'T11 * 'T12 * 'T13 * 'T14 -> unit

Full name: System.Action<_,_,_,_,_,_,_,_,_,_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6,'T7,'T8,'T9,'T10,'T11,'T12,'T13,'T14,'T15> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 * 'T7 * 'T8 * 'T9 * 'T10 * 'T11 * 'T12 * 'T13 * 'T14 * 'T15 -> unit

Full name: System.Action<_,_,_,_,_,_,_,_,_,_,_,_,_,_,_>

--------------------
type Action<'T1,'T2,'T3,'T4,'T5,'T6,'T7,'T8,'T9,'T10,'T11,'T12,'T13,'T14,'T15,'T16> =
  delegate of 'T1 * 'T2 * 'T3 * 'T4 * 'T5 * 'T6 * 'T7 * 'T8 * 'T9 * 'T10 * 'T11 * 'T12 * 'T13 * 'T14 * 'T15 * 'T16 -> unit

Full name: System.Action<_,_,_,_,_,_,_,_,_,_,_,_,_,_,_,_>

val synchronizationContext : SynchronizationContext

Multiple items
type SynchronizationContext =
  new : unit -> SynchronizationContext
  member CreateCopy : unit -> SynchronizationContext
  member IsWaitNotificationRequired : unit -> bool
  member OperationCompleted : unit -> unit
  member OperationStarted : unit -> unit
  member Post : d:SendOrPostCallback * state:obj -> unit
  member Send : d:SendOrPostCallback * state:obj -> unit
  member Wait : waitHandles:nativeint[] * waitAll:bool * millisecondsTimeout:int -> int
  static member Current : SynchronizationContext
  static member SetSynchronizationContext : syncContext:SynchronizationContext -> unit

Full name: System.Threading.SynchronizationContext

--------------------
SynchronizationContext() : unit

property SynchronizationContext.Current: SynchronizationContext

val doInOriginalThread : (('a -> unit) -> 'a -> unit)

val arg : 'a

SynchronizationContext.Post(d: SendOrPostCallback, state: obj) : unit

Action.Invoke(obj: 'a) : unit