使用guards和where子句的函数然后我想用递归来改变它

Question

我正在尝试实现一个功能，可以检查分数和类中所有分数的列表，然后告诉你通过生成一个字符串你得到的是你高于平均水平。它应该如下面的表达式：

scoreChecker 45 [19,33,40,66,11,77]  ==  "You're better than average!!"
scoreChecker 30 [19,33,40,66,11,77]  ==  "Sorry, you're below the average :-("
scoreChecker 41 [19,33,40,66,11,77]  ==  "Precisely average"
scoreChecker 100 []                  ==  "Sorry, you're not using it correctly"

我的尝试就是这样，但我收到了一个错误：

scoreChecker :: Double -> [Double] -> String
scoreChecker _ [] = "Sorry, you're not using it correctly"
scoreChecker avg (x:xs)
| x <= xs   = "You're better than average!!"
| x == xs    = "Precisely average"
| otherwise avg  = "Sorry, you're below the average :-(" 
     where 
           scores       = [19,33,40,66,11,77]
            avg         = scores / length

我希望有些专家会帮忙，我第一次学习这门语言。 谢谢大家。

我的输出：

parse error on input `='

Answer 1

请注意以下内容......

• 该功能应始终有两个输入......但第二种情况有一个。

• xs是一个列表，avg不是。你如何在这些之间使用（＆lt; =）。

• 您对avg的定义在数学上并不正确。