hashtags in Haskell

Hashtags.hs

import Data.Char (isAlpha)
import Text.Parsec

-- | Parses exactly one hashtag (and nothing else).
hashtag = do
  char '#'
  many letter

-- | Parse hashtags from a string (see the previous version for
--   a list-based version).
hashtags :: String -> [String]
hashtags s = always [] parsed
  where parsed = parse (sepBy hashtag noTag) "hashtags" s

-- | Parse many things that aren't '#'.
noTag = many $ noneOf "#"

-- | When the Either is a Left, always return x. Otherwise, simply
--   unwrap the Right value.
always :: c -> Either a c -> c
always x = either (const x) id