Pattern matching for Vector using PatternSynonyms in Haskell

VectorPattern.hs

{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE PatternSynonyms #-}

import Data.Vector as V

pattern Empty :: Vector a
pattern Empty <- (V.null -> True) where Empty = V.empty 

uncons :: Vector a -> Maybe (a, Vector a)
uncons Empty = Nothing
uncons v     = Just (unsafeHead v, unsafeTail v)

pattern (:<|)  :: a -> Vector a -> Vector a
pattern x :<| xs <- (uncons -> Just (x, xs))

pattern (:|>) :: Vector a -> a -> Vector a 
pattern xs :|> x <- (unsnoc -> Just (xs, x))

vsum :: Num a => Vector a -> a 
vsum Empty = 0
vsum (x :|> xs) = x + vsum xs