CommandParser.hs

{-# LANGUAGE OverloadedStrings #-}

module CommandParser where
  import Data.Attoparsec.Char8
  import Control.Applicative
  import qualified Data.Text.Lazy as L
  import Data.Text.Encoding

  data Command = Retrieve | Delete | New deriving Show

  parseCommand :: Parser Command
  parseCommand =
        (string "Retrieve"    >> return Retrieve)
    <|> (string "Delete"      >> return Delete)
    <|> (string "New"         >> return New)

  parse :: L.Text -> Either String Command
  parse s = parseOnly parseCommand ((encodeUtf8 . L.toStrict) s)