输入`='解析错误 - Haskell

Question

我在运行这个Haskell代码时遇到了这个非常烦人的错误.由于某种原因,它不喜欢第一行delLast :: (Ord a) => [a] -> [a]

delLast :: (Ord a) => [a] -> [a]
delLast [] = []
delLast (x:[]) = []
delLast (x:xs) = [x] ++ delLast xs

任何人都知道为什么我得到这个错误？谢谢.

这是我得到的错误:

parse error on input `='
Failed, modules loaded: none.

Answer 1

紧接在该行之前是否有未定的定义？

x = do

delLast :: (Ord a) => [a] -> [a]
delLast [] = []
delLast (x:[]) = []
delLast (x:xs) = [x] ++ delLast xs

编译给我:

test.hs:5:12: parse error on input `='