updateMax Map/IntMap discrepancy

[meooow25]

updateMax, updateMaxWithKey, updateMin, updateMinWithKey for lazy and strict IntMap do not agree with Map.

IntMap errors on an empty map:

containers/containers/src/Data/IntMap/Internal.hs

Lines 2180 to 2189 in 7e7ce15

	updateMinWithKey :: (Key -> a -> Maybe a) -> IntMap a -> IntMap a
	updateMinWithKey f t =
	case t of Bin p l r | signBranch p -> binCheckRight p l (go f r)
	_ -> go f t
	where
	go f' (Bin p l r) = binCheckLeft p (go f' l) r
	go f' (Tip k y) = case f' k y of
	Just y' -> Tip k y'
	Nothing -> Nil
	go _ Nil = error "updateMinWithKey Nil"

Map simply returns the empty map:

containers/containers/src/Data/Map/Internal.hs

Lines 1744 to 1749 in 7e7ce15

	updateMinWithKey :: (k -> a -> Maybe a) -> Map k a -> Map k a
	updateMinWithKey _ Tip = Tip
	updateMinWithKey f (Bin sx kx x Tip r) = case f kx x of
	Nothing -> r
	Just x' -> Bin sx kx x' Tip r
	updateMinWithKey f (Bin _ kx x l r) = balanceR kx x (updateMinWithKey f l) r

The better option is that IntMap also returns an empty map.

---

Historical note: The Map behavior has been so since it was added in bbbba97. updateMax and friends for IntMap were added a bit later in 1a2cf0f.

[meooow25]

Discovered when writing IntMap strictness tests for #1019