Hello! I am trying to implement a binary search function that returns the index of an exact or the (index + 1) where the item should be inserted in an array if the item to be searched is not found (I am not trying to insert data in the array) . Right now, the bottleneck of my program is in binarySearch', the function must be called a few billion times. Do you have any ideas on how to improve the performance of this function? import Data.Array.IArray type IntArray a = Array Int a -- The array must be 0 indexed. binarySearch :: Ord a => a -> IntArray a -> Int binarySearch query array = let (low, high) = bounds array in binarySearch' query array low high binarySearch' :: Ord a => a -> IntArray a -> Int -> Int -> Int binarySearch' query array !low !high | low <= high = let ! mid = low + ((high - low) `div` 2) ! midVal = array ! mid in next mid midVal | otherwise = -(low + 1) where next mid midVal | midVal < query = binarySearch' query array (mid + 1) high | midVal > query = binarySearch' query array low (mid - 1) | otherwise = mid Thank you! Arnoldo Muller