应用程序类型中的类型错误不匹配
nextMyStates :: MyState -> [MyState]
nextMyStates(s) =[up(s),down(s),left(s),right(s),collect(s)]
isGoal :: MyState -> Bool
isGoal (S (l) (al) d z) = if al == [] then True else False
search :: [MyState] -> MyState
search (s:sz) | isGoal s = s
| otherwise = search (sz) ++ nextMyStates s
我正在尝试运行此类型错误，但出现此类型错误，
Type error in application
*** Expression : search sz ++ nextMyStates s
*** Term : search sz
*** Type : MyState
*** Does not match : [MyState]
我认为此符号（S：SZ）意味着SZ是一个由头部以外的元素组成的列表
nextMyStates :: MyState -> [MyState]
nextMyStates(s) =[up(s),down(s),left(s),right(s),collect(s)]
isGoal :: MyState -> Bool
isGoal (S (l) (al) d z) = if al == [] then True else False
search :: [MyState] -> MyState
search (s:sz) | isGoal s = s
| otherwise = search (sz) ++ nextMyStates s
I am trying to run this but this type error comes up
Type error in application
*** Expression : search sz ++ nextMyStates s
*** Term : search sz
*** Type : MyState
*** Does not match : [MyState]
I thought this notation (s:sz) meant the sz is a list consisting of the rest of the elements besides the head but it says it is a single element not a list
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