SML 运算符和操作数中的快速排序不一致错误

Quicksort in SML operator and operand don't agree error

我正在尝试编写

类型的快速排序函数
'a list * ('a * 'a -> bool) -> 'a list

但出于某种原因我得到:

'a list -> ('a * 'a -> bool) -> 'a list

这是我的函数代码:

fun quicksort xs f = let
   fun qs [] = []
     | qs [x] = [x]
    | qs (p::xs) = let
        val (less, more) = List.partition (fn x => f (x, p)) xs
        in
          qs less @ p :: qs more
        end
   in
     qs xs
   end

当我调用该函数时出现此错误:

stdIn:73.1-73.18 Error: operator and operand don't agree [tycon mismatch]
  operator domain: 'Z list
  operand:         int list * (int * int -> bool)
  in expression:
    quicksort (L, op <)

我意识到我一定是传错了,但我就是看不到我的错误。所以,我的问题是这里发生了什么,我在尝试传递我的列表和运算符时收到此错误?

您可以简单地更改:

fun quicksort xs f = let 

至:

fun quicksort (xs,f) = let

因为您希望快速排序将元组 (xs,f) 作为参数。