Fix _fillTexture lens by using Maybe.

src/Diagrams/TwoD/Arrow.hs

@@ -228,17 +228,17 @@ lengths f opts = (\h t -> opts & headLength .~ h & tailLength .~ t) <$> f (opts
 --   color to blue. For more general control over the style of arrowheads,
 --   see 'headStyle'.
 headTexture :: TypeableFloat n => Lens' (ArrowOpts n) (Texture n)
-headTexture = headStyle . _fillTexture
+headTexture = headStyle . atTAttr . anon def (const False) . _FillTexture . committed
 
 -- | A lens for setting or modifying the texture of an arrow
 --   tail. This is *not* a valid lens (see 'committed').
 tailTexture :: TypeableFloat n => Lens' (ArrowOpts n) (Texture n)
-tailTexture = tailStyle . _fillTexture
+tailTexture = tailStyle . atTAttr . anon def (const False) . _FillTexture . committed
 
 -- | A lens for setting or modifying the texture of an arrow
 --   shaft.
 shaftTexture :: TypeableFloat n => Lens' (ArrowOpts n) (Texture n)
-shaftTexture = shaftStyle . _lineTexture
+shaftTexture = shaftStyle . atTAttr . anon def (const False) . _LineTexture
 
 -- Set the default shaft style of an `ArrowOpts` record by applying the
 -- default style after all other styles have been applied.

src/Diagrams/TwoD/Attributes.hs

@@ -362,17 +362,14 @@ fillTexture = applyTAttr . mkFillTexture
 mkFillTexture :: Texture n -> FillTexture n
 mkFillTexture = FillTexture . Commit . Last
 
--- | Lens onto the 'Recommend' of a fill texture in a style.
-_fillTextureR :: (Typeable n, Floating n) => Lens' (Style V2 n) (Recommend (Texture n))
-_fillTextureR = atTAttr . anon def isDef . _FillTexture
-  where
-    isDef (FillTexture (Recommend (Last (SC sc)))) = toAlphaColour sc == transparent
-    isDef _                                        = False
+-- | Lens onto the possible recommend of a fill texture in a style.
+_fillTextureR :: (Typeable n, Floating n) => Lens' (Style V2 n) (Maybe (Recommend (Texture n)))
+_fillTextureR = atTAttr . mapping _FillTexture
 
 -- | Commit a fill texture in a style. This is *not* a valid lens
 --   because the resulting texture is always 'Commit' (see 'committed').
-_fillTexture :: (Typeable n, Floating n) => Lens' (Style V2 n) (Texture n)
-_fillTexture = _fillTextureR . committed
+_fillTexture :: (Typeable n, Floating n) => Lens' (Style V2 n) (Maybe (Texture n))
+_fillTexture = _fillTextureR . mapping committed
 
 -- | Set the fill color.  This function is polymorphic in the color
 --   type (so it can be used with either 'Colour' or 'AlphaColour'),