er targeted by a 'Fold'.
--
-- >>> productOf both (4,5)
-- 20
-- >>> productOf folded [1,2,3,4,5]
-- 120
--
-- @
-- 'Data.Foldable.product' ≡ 'productOf' 'folded'
-- @
--
-- This operation may be more strict than you would expect. If you
-- want a lazier version use @'ala' 'Product' '.' 'foldMapOf'@
--
-- @
-- 'productOf' :: 'Num' a => 'Getter' s a     -> s -> a
-- 'productOf' :: 'Num' a => 'Fold' s a       -> s -> a
-- 'productOf' :: 'Num' a => 'Lens'' s a      -> s -> a
-- 'productOf' :: 'Num' a => 'Iso'' s a       -> s -> a
-- 'productOf' :: 'Num' a => 'Traversal'' s a -> s -> a
-- 'productOf' :: 'Num' a => 'Prism'' s a     -> s -> a
-- @
productOf :: Num a => Getting (Endo (Endo a)) s a -> s -> a
productOf l = foldlOf' l (*) 1
{-# INLINE productOf #-}

-- | Calculate th
productOf :: Num a => Getting (Endo (Endo a)) s a -> s -> a
productOf l = foldlOf' l (*) 1
productOf l = foldlOf' l (*) 1