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我是F#的新手,很抱歉,如果这看起来太愚蠢。我试图通过FileSystemWatcher
收听文件创建和删除事件。现在我想创建一个观察者来显示基于目录中添加和删除的文件的更改计数。所以每当一个文件被添加到目录时,计数就会增加一个,并在文件被删除时减少。我下面的代码:此表达式预计有FSI_0024.xxx类型,但这里有类型FSI_0017.xxx
let watcher = new FileSystemWatcher(@".")
watcher.EnableRaisingEvents <- true
let created = watcher.Created
let deleted = watcher.Deleted
type Change =
| Addition of string
| Removal of string
let a = created |> Observable.map (fun eventArgs ->
Addition eventArgs.Name)
let r = deleted |> Observable.map (fun eventArgs ->
Removal eventArgs.Name)
let changes = Observable.merge a r
let collector count state =
match state with
| Addition x -> count + 1
| Removal x -> count - 1
let createdCount =
changes |> Observable.scan (fun count s -> collector count s) 0
但它提供了以下错误的Observable.scan
:
This expression was expected to have type
FSI_0024.Change
but here has type
FSI_0017.Change
类型是相同的,但我不明白这FSI_xxxx部分。什么可能是一个问题?
重置您的fsi会话。有一些旧的定义在附近引起问题 –
@JohnPalmer谢谢先生,因为节省了我的时间。 –