list - F#选择对随机整数列表进行排序

Question

我是F＃的新手，试图弄清楚一些基本知识，但步伐缓慢。在下面的代码中，我试图生成一个随机整数列表，然后对其进行排序。

let randomNumberList count =
    let r = System.Random()
    List.init count (fun _ -> r.Next(100))

let rec selectionSort l = function
    | [] -> []
    | l -> let min = List.min l in
           let rest = List.filter (fun i -> i <> min) l in
           let sortedList = selectionSort rest in
           min :: sortedList
sortedList = selectionSort l

let unsortedList = randomNumberList 10
printfn "%A" unsortedList
printfn "%A" sortedList

所以两件事...一是我得到的错误:

stdin(515,19): error FS0001: This expression was expected to have type
    'a list    
but here has type
    'a list -> 'a list

另一个是随机数列表。它可以工作，但是我希望生成的数字小于100，而不是我现在得到的庞大值。

感谢您的耐心配合和帮助!

Answer 1

如评论中所述，l中不需要let rec selectionSort。固定代码:

let randomNumberList count =
    let r = System.Random()
    List.init count (fun _ -> r.Next(100))

let rec selectionSort = function
    | [] -> []
    | l -> let min = List.min l in
           let rest = List.filter (fun i -> i <> min) l in
           let sortedList = selectionSort rest in
           min :: sortedList

let unsortedList = randomNumberList 10
let sortedList = selectionSort unsortedList
printfn "%A" unsortedList
printfn "%A" sortedList
System.Console.ReadLine() |> ignore

说明:

let vname = function
   | ... -> ...
   | ... -> ...

是...的缩写

let vname arg = match arg with
   | ... -> ...
   | ... -> ...