Length check in sameArray1 is redundant

[sjakobi]

unordered-containers/Data/HashMap/Internal/Array.hs

Lines 139 to 151 in 0a474c7

	sameArray1 :: (a -> b -> Bool) -> Array a -> Array b -> Bool
	sameArray1 eq !xs0 !ys0
	| lenxs /= lenys = False
	| otherwise = go 0 xs0 ys0
	where
	go !k !xs !ys
	| k == lenxs = True
	| (# x #) <- index# xs k
	, (# y #) <- index# ys k
	= eq x y && go (k + 1) xs ys
	!lenxs = length xs0
	!lenys = length ys0

The sameArray1 function used in equal1 and equalKeys compares the lengths of the two arrays as a first step. This is unnecessary because in both use-cases the lengths are known to equal because the corresponding bitmaps are the same or because the array of a Full node is known to have size maxChildren.

unordered-containers/Data/HashMap/Internal.hs

Lines 421 to 435 in 8c20f7a

	equal1 :: Eq k
	=> (v -> v' -> Bool)
	-> HashMap k v -> HashMap k v' -> Bool
	equal1 eq = go
	where
	go Empty Empty = True
	go (BitmapIndexed bm1 ary1) (BitmapIndexed bm2 ary2)
	= bm1 == bm2 && A.sameArray1 go ary1 ary2
	go (Leaf h1 l1) (Leaf h2 l2) = h1 == h2 && leafEq l1 l2
	go (Full ary1) (Full ary2) = A.sameArray1 go ary1 ary2
	go (Collision h1 ary1) (Collision h2 ary2)
	= h1 == h2 && isPermutationBy leafEq (A.toList ary1) (A.toList ary2)
	go _ _ = False
	leafEq (L k1 v1) (L k2 v2) = k1 == k2 && eq v1 v2