Use strict tuples for SPics

src/ShapePicture.hs

@@ -13,22 +13,23 @@ module ShapePicture
 --    , mirrorSPxz
     , overPosSP
     ) where
+
 import ShapePicture.Data
 import Shape
 import Picture
 import Geometry
-
+import Data.Strict.Tuple
 import Data.Bifunctor
 --import Control.Lens
 
 -- should all this be inlined/inlinable?
 noPic :: Shape -> SPic
 {-# INLINE noPic #-}
-noPic = (,mempty)
+noPic = (:!: mempty)
 
 noShape :: Picture -> SPic
 {-# INLINE noShape #-}
-noShape = (mempty,)
+noShape = (mempty :!:)
 
 --_spShape :: SPic -> Shape
 --_spShape = fst