Fix wrong complexity of IntMap.alter.

This resolves #165.

Author: foxik

Data/IntMap/Strict.hs

@@ -505,7 +505,7 @@ updateLookupWithKey f0 k0 t0 = k0 `seq` toPair $ go f0 k0 t0
 
 
 
--- | /O(log n)/. The expression (@'alter' f k map@) alters the value @x@ at @k@, or absence thereof.
+-- | /O(min(n,W))/. The expression (@'alter' f k map@) alters the value @x@ at @k@, or absence thereof.
 -- 'alter' can be used to insert, delete, or update a value in an 'IntMap'.
 -- In short : @'lookup' k ('alter' f k m) = f ('lookup' k m)@.
 alter :: (Maybe a -> Maybe a) -> Key -> IntMap a -> IntMap a