module Utils =
	// (...)
	type MaybeBuilder() =
        member this.Bind(x,f) = Option.bind f x
        member this.Return(x) = Some x
    let maybe = new MaybeBuilder()

// inny moduł
type FileViewModel =
	// (...)
    member this.OriginalNumSamples 
        with get() = Utils.maybe {
            let! f = file
            return Signal.length f.spectrogram.samples
        
// alternatywą by było
type FileViewModel =
	// (...)
    member this.OriginalNumSamples 
        with get() = Option.map ( fun (f: File.Raw) -> Signal.length f.spectrogram.samples ) file