, attoparsec

import           Data.Bifunctor      (bimap, first)

import Data.Attoparsec.Text (anyChar, parseOnly, endOfInput)
import qualified Data.Attoparsec.Text as Atto
import           Data.Bifunctor       (bimap, first)

        char = argument auto . metavar

        char = argument singleChar . metavar
singleChar :: ReadM Char
singleChar = eitherReader $
    first parseError . (parseOnly oneChar . Text.pack)
    where
        parseError = const "Expecting a single character"
        oneChar = anyChar <* endOfInput