Question

我一直在采样由Tomas Petricek编写的F＃片段，它返回一个可观察到的滑动窗口包含从输入可观察对象中提取的元素。当传递给函数的IObservable包含int或元组时，它可以正常工作，但是如果它是一个IObservable记录，那么'count'元素的每个结果数组（窗口）都包含相同的值。并且每个新窗口包含与观察到的最后一个值相同的“count”元素。该片段在下面复制。异步表达式内部是否存在可能导致此行为的F＃记录？

open System

module Observable =

  /// Returns an observable that yields sliding windows of 
  /// containing elements drawn from the input observable. 
  /// Each window is returned as a fresh array.
  let windowed (count:int) (source:IObservable<_>) =
    { new IObservable<_> with
        member x.Subscribe(observer) =
          // Start an agent that remembers partial windows of length 
          // smaller than the count (new agent for every observer)
          let agent = MailboxProcessor.Start(fun agent ->
            // The parameter 'lists' contains partial lists and their lengths
            let rec loop lists = async { 
              // Receive the next value
              let! value = agent.Receive()

              // Add new empty list and then the new element to all lists.
              // Then split the lists into 'full' that should be sent
              // to the observer and 'partial' which need more elements.
              let full, partial =
                ((0, []) :: lists)
                |> List.map (fun (length, l) -> length + 1, value::l)
                |> List.partition (fun (length, l) -> length = count)

              // Send all full lists to the observer (as arrays)
              for (_, l) in full do
                observer.OnNext(l |> Array.ofSeq |> Array.rev) 
              // Continue looping with incomplete lists
              return! loop partial }

            // Start with an empty list of partial lists
            loop [])

          // Send incoming values to the agent
          source.Subscribe(agent.Post) }

Answer 1

感谢。看起来像使用System.Reactive更简单的实现，而不是从MSDN for Control.Observable上的文档中的ObservableSource的自定义实现确实按预期工作。但是，那个例子可能存在一些问题。

F＃Sliding Window Agent不使用记录

1 个答案: