哈斯克爾多行lambda表達式

Question

我從learnyouahaskell.com學習Haskell和存在使得例如：

search :: (Eq a) => [a] -> [a] -> Bool 
search needle haystack = 
    let nlen = length needle 
    in foldl (\acc x - 
> if take nlen x == needle then True else acc) False (tails haystack) 

但是，當嘗試這種代碼GHC，它給了我

error: parse error on input ‘-’ 

但它的工作原理是這樣的：

search :: (Eq a) => [a] -> [a] -> Bool 
search needle haystack = 
    let nlen = length needle 
    in foldl (\acc x -> if take nlen x == needle then True else acc) False (tails haystack) 

是否有Haskell的功能，允許多行lambda或是索姆我錯過了什麼？

Answer 1

不要打破->

只要做到：

search :: (Eq a) => [a] -> [a] -> Bool 
search needle haystack = 
    let nlen = length needle 
    in foldl (\acc x -> 
if take nlen x == needle then True else acc) False (tails haystack) 

或

search :: (Eq a) => [a] -> [a] -> Bool 
search needle haystack = 
    let nlen = length needle 
    in foldl (\acc x 
-> if take nlen x == needle then True else acc) False (tails haystack)