How to use view patterns

ViewPatterns.hs

{-# LANGUAGE PatternGuards #-}
{-# LANGUAGE ViewPatterns #-}
module ViewPatterns where
import Data.List

data EMail  = EMail User Domain deriving Show
type User   = String
type Domain = String

view :: String -> Maybe EMail
view ss
  | (user@(_:_), _:domain)
      <- break (== '@') ss = Just (EMail user domain)
view _                     = Nothing

email :: String -> Maybe EMail
email (view -> x) = x