p_fPrim :: (Double -> Double) -> [Const] -> Maybe Const
p_fPrim f [Fl x] = Just $ Fl (f x)
p_fPrim :: (Double -> Double) -> [Const] -> Maybe Const
p_fPrim f [Fl x] = Just $ Fl (f x)
p_fPrim f [Fl x] = Just $ Fl (f x)