onBeziers :: ([Curve] -> [Curve] -> [Curve])
             -> FrozenPath -> FrozenPath -> FrozenPath
onBeziers op p' q' = fromBeziers $ op (toBeziers p') (toBeziers q')
onBeziers :: ([Curve] -> [Curve] -> [Curve])
             -> FrozenPath -> FrozenPath -> FrozenPath
onBeziers op p' q' = fromBeziers $ op (toBeziers p') (toBeziers q')
onBeziers op p' q' = fromBeziers $ op (toBeziers p') (toBeziers q')