0
我有一個字符串,我需要解析爲Array或其他數組。Haskell:通過解析數據類型錯誤
這是我的代碼有
import Test.HUnit (runTestTT,Test(TestLabel,TestList),(~?=))
import qualified Text.Parsec as P (char,runP,noneOf,many,(<|>),eof)
import Text.ParserCombinators.Parsec
import Text.Parsec.String
import Text.Parsec.Char
import Text.PrettyPrint.HughesPJ
import Data.Maybe
import Data.List.Split
newtype CSV = CSV [Row] deriving (Show,Eq)
type Row = [String]
parseCSV :: Parser CSV
parseCSV = error "not done yet"
runParsec :: Parser a -> String -> Maybe a
runParsec parser input = case P.runP parser() "" input of
Left _ -> Nothing
Right a -> Just a
當我開始實現parseCSV功能
parseCSV = Just (CSV [[""]])
我得到這個錯誤:
Expected type: Parser CSV
Actual type: Maybe CSV
它的工作!我會在幾分鐘內將其標記爲正確答案,謝謝! –