Question

这是我的电影数据类型的代码和保存它的数据库

data Film = String [String] Int [String]
    deriving (Eq,Ord,Show,Read) 

testDatabase :: [Film]
testDatabase = ["Casino Royale" 
"Daniel Craig", "Eva Green", "Judi Dench"
2006
"Garry", "Dave", "Zoe", "Kevin", "Emma"

"Cowboys & Aliens"
"Harrison Ford", "Daniel Craig", "Olivia Wilde"
2011
"Bill", "Jo", "Garry", "Kevin", "Olga", "Liz"]

我不断收到此错误

parse error (possibly incorrect indentation or mismatched brackets)

不知道为什么给我那个。不帮忙吗？

Answer 1

问题与列表中的缩进有关。 Haskell非常关心空白，如果继续第二行，那么你需要缩进。另外，请确保您的字符串列表实际上是列表。另一个问题是您需要在数据声明中使用构造函数。尝试这样的事情：

data Film = Film String [String] Int [String]
    deriving (Eq,Ord,Show,Read) 

testDatabase :: [Film]
testDatabase = [Film "Casino Royale" 
    ["Daniel Craig", "Eva Green", "Judi Dench"]
    2006
    ["Garry", "Dave", "Zoe", "Kevin", "Emma"]
    , Film "Cowboys & Aliens"
    ["Harrison Ford", "Daniel Craig", "Olivia Wilde"]
    2011
    ["Bill", "Jo", "Garry", "Kevin", "Olga", "Liz"]]

Haskell：语法错误

1 个答案: