F#查找过去5天内修改的子目录中的所有文件

Question

我对F#很新,所以请保持温柔.我试图用函数式编写代码来查看过去5天内修改过的所有文件的目录(和子目录),然后对这些文件执行某些操作(此时只是将名称写入控制台) .

我的代码是:

open System.IO

let rec getAllFiles dir pattern =
    seq { yield! Directory.EnumerateFiles(dir, pattern)
          for d in Directory.EnumerateDirectories(dir) do
              yield! getAllFiles d pattern }

let printMe x = printfn "%A" x

let hasChangedRecently fileName =
    let myFile = System.IO.FileInfo(fileName)
    let f myFile = function
    | myFile when myFile.LastWriteTime >= System.DateTime.Parse "10-04-2015" -> printMe MyFile.Name
    | _ -> ()

    f fileName

[<EntryPoint>]
let main argv =
    getAllFiles @"c:\temp" "*.xml"
    |> Seq.iter hasChangedRecently

    System.Console.ReadKey() |> ignore
    0 // return an integer exit code

hasChangedRecently块中出错了.

错误是:

myFile.LastWriteTime
Lookup on object of indeterminate type based on information prior to this program point. A type annotation may be needed prior to this program point to constrain the type of the object. This may allow the lookup to be resolved.

MyFile.Name
The namespace or module 'MyFile' is not defined

|> Seq.iter hasChangedRecently
Type mismatch. Expecting a
string -> unit    
but given a
string -> 'a -> unit    
The type 'unit' does not match the type ''a -> unit'

我很确定这些是基本的错误,但会真诚地感谢一些指导.

Answer 1

我想改变的hasRecentlyChanged是string -> bool功能和过滤器,它的文件,然后有一个单独的功能打印文件.

let hasChangedRecently fileName =
    let myFile = System.IO.FileInfo(fileName)
    myFile.LastWriteTime >= System.DateTime.Parse "10-04-2015"

let printFile file =
    printfn "%s" file

并在main:

getAllFiles @"c:\temp" "*.xml"
|> Seq.filter hasChangedRecently
|> Seq.iter printFile

此外,如果您愿意,可以getAllFiles通过使用SearchOption.AllDirectories内置的.NET 来避免递归:

Directory.EnumerateFiles(dir, pattern, SearchOption.AllDirectories)