替换句子中的单词

Question

我有一个作业，我必须在Haskell的给定句子中更改和省略某些单词。例如：

输入：

Give me the nippers, please!

输出：

Giv me the tippers!

and here is my attempt:

    replaceWord [] = []
    replaceWord(x:xs)
       |x == "Give" = "Giv" : replaceWord xs
       |x == "me" = "mi" : replaceWord xs
       |otherwise = x : replaceWord xs
       where (x:xs) = words (x:xs) 


I became an error message saying:
 "Couldn't match type ‘[Char]’ with ‘Char’
      Expected type: [Char]
      Actual type: [String] • In the expression: words (x : xs)
      In a pattern binding: (x : xs) = words (x : xs)
      In an equation for ‘replaceWord’:
          replaceWord (x : xs)
            | x == "Geben" = "Gib" : replaceWord xs
            | x == "Sie" = "mi" : replaceWord xs
            | otherwise = x : replaceWord
            where
                (x : xs) = words (x : xs)
  |
9 |  where (x:xs) = words (x:xs)    | "   

I can not figure out how to use pattern match and how to change a string in to a list made of words. I have to use recursion and pattern matching and not allowed to use list functions such as map, filter, concat, etc. 

Any suggestions?