{-# LANGUAGE PatternSynonyms #-}

pattern Head x <- x:xs

pattern Head' x
  <- x:xs

pattern Head''{x}
  <- x:xs

pattern FirstTwo{x,y}
  <- x : (y : xs)

pattern FirstTwo'{x
                 , y} <- x : (y:xs)

pattern Simple <- "Simple"

pattern WithTypeSig :: String
pattern WithTypeSig <- "WithTypeSig"