在haskell中错误使用逻辑运算符？

Question

我是哈斯凯尔的新人。我尝试编译一些例子，但我不知道编译器试图告诉我什么。 这是我的代码：

import Data.List
import System.IO

max' :: int->int->int
max' n m 
        | (n <= m) = m
        | otherwise = n

maximum' :: [int]->int
maximum' [a]=a
maximum' (x:xs) = max' x (maximum' xs)

sort' :: [int]->[int]
sort' [] =[]
sort' (x:xs) = sort'[y|y<-(x:xs),y < maximum'(x:xs)]++[y'|y'<-(x:xs),y' == maximum'(x:xs)]

，这是编译器的输出：

Prelude> :r
[1 of 1] Compiling Main             ( test.hs, interpreted )
Failed, modules loaded: none.

test.hs:6:22:
    No instance for (Ord int) arising from a use of ‘<=’
    Possible fix:
      add (Ord int) to the context of
        the type signature for max' :: int -> int -> int
    In the expression: (n <= m)
    In a stmt of a pattern guard for
                   an equation for ‘max'’:
      (n <= m)
    In an equation for ‘max'’:
        max' n m
          | (n <= m) = m
          | otherwise = n

test.hs:15:36:
    No instance for (Ord int) arising from a use of ‘<’
    Possible fix:
      add (Ord int) to the context of
        the type signature for sort' :: [int] -> [int]
    In the expression: y < maximum' (x : xs)
    In a stmt of a list comprehension: y < maximum' (x : xs)
    In the first argument of ‘sort'’, namely
      ‘[y | y <- (x : xs), y < maximum' (x : xs)]’

test.hs:15:73:
    No instance for (Eq int) arising from a use of ‘==’
    Possible fix:
      add (Eq int) to the context of
        the type signature for sort' :: [int] -> [int]
    In the expression: y' == maximum' (x : xs)
    In a stmt of a list comprehension: y' == maximum' (x : xs)
    In the second argument of ‘(++)’, namely
      ‘[y' | y' <- (x : xs), y' == maximum' (x : xs)]’

编译器指向我代码中的所有逻辑运算符