haskell being a bitch.hs

personExists :: Person -> Bool
personExists (Person id name lastname password) = do
    let
        database = "database.txt"
    
    contents <- readFile database
    if (contents > 0) then do
        let
            (x:xs) = splitOn "\n" contents
            person = id ++ ";" ++ name ++ ";" ++ lastname ++ ";" ++ password
            
            existsInList person [] = False
            existsInList person (x:xs) | person == x = True
                                       | otherwise = existsInList person xs
-- issue is on this "in" ; Storage.hs:36:9: error: parse error on input `in'
        in existsInList person (x:xs)

    else False