Main.hs

  {-# LANGUAGE OverloadedStrings #-}
_
  import qualified Data.ByteString.Lazy          as BL
  import           Data.Csv
  import qualified Data.Vector                   as V
~ import           Data.Char

  data RedirectMap= RedirectMap
      { badUrl :: String
      , goodUrl :: String
      }

  myOptions :: DecodeOptions
  myOptions = defaultDecodeOptions { decDelimiter = fromIntegral (ord '\t') }

  instance FromNamedRecord RedirectMap where
      parseNamedRecord r = RedirectMap <$> r .: "badUrl" <*> r .: "goodUrl"

  main :: IO ()
  main = do
~     xs <- readInUrls
~     print $ show xs
~
~ readInUrls = do
~     csvData <- BL.readFile "test.tsv"
~     case decodeByNameWith myOptions csvData of
~         Left  err    -> pure ([] :: [(String, String)])
~         Right (_, v) -> pure . V.toList $ V.map redirectMapToPair v
~
~
~ redirectMapToPair :: RedirectMap -> (String, String)
~_redirectMapToPair (RedirectMap bad good) = (,) bad good