hltFilteredBy :: (a -> Bool)  -- ^ hit test condition
              -> [a]          -- ^ strokes to test 
              -> AlterList (NotHitted a) (Hitted a)
hltFilteredBy test is = evalState (hltFilteredBy_StateT test is) False
hltFilteredBy :: (a -> Bool)  -- ^ hit test condition
              -> [a]          -- ^ strokes to test 
              -> AlterList (NotHitted a) (Hitted a)
hltFilteredBy test is = evalState (hltFilteredBy_StateT test is) False
hltFilteredBy test is = evalState (hltFilteredBy_StateT test is) False