priority = option 0 (do{ d <- digit ; return (digitToInt d) })
nameParser = option str ( long "name" <> short 'n' )
priority = option 0 (digitToInt <$> digit)
priority = option 0 (do{ d <- digit ; return (digitToInt d) })
priority = option 0 (digitToInt <$> digit)
>>> match (option "1" <> "2") "12" ["12"] >>> match (option "1" <> "2") "2" ["2"]
option a p = p // unit a