小编dan*_*n p的帖子

这让我很难过.

我已经阅读了关于这个主题的SO帖子:这里是最相关的,但它没有涵盖将代表传递给一个事件(尽管我预计它会很简单).

具体来说,VS中的错误是:

This function value is being used to construct a delegate type whose signature includes a byref argument. You must use an explicit lambda expression taking 2 arguments.

我能找到的错误的最佳推理是在Eric Lippert的博客中,但我认为我已经在下面处理了它.

// Documentation: http://msdn.microsoft.com/en-us/library/aa752084(v=vs.85).aspx    
// Don't forget to unwrap the instance before using it.
let mutable ieInstance : option<InternetExplorer> = None

let onDocumentComplete (pDisp : Object) (url : byref<Object>) =
    let doc = ieInstance.Value.Document :?> IHTMLDocument2
    let window = doc.parentWindow
    window.execScript(@"alert('Message added by addon.');") |> …

我已经编写了该length函数的六个版本。一些性能差异是有道理的，但其中一些似乎根本不同意我读过的文章（例如this one和this one）。

-- len1 and lenFold1 should have equivalent performance, right?

len1 :: [a] -> Integer
len1 [] = 0
len1 (x:xs) = len1 xs + 1

lenFold1 :: [a] -> Integer
lenFold1 = foldr (\_ a -> a + 1) 0


-- len2 and lenFold2 should have equivalent performance, right?

len2 :: [a] -> Integer
len2 xs = go xs 0 where
  go [] acc = acc
  go (x:xs) acc = go …