Delete element in Haskell

In Haskell, arrays are immutable, i.e., they cannot be changed once they are created. Therefore, it is not possible to delete an element from an array. However, you can create a new array that contains all the elements of the original array except for the one you want to remove.

Here's an example of how to achieve this:

import Data.Array
deleteElement :: Int -> Array Int a -> Array Int a

deleteElement index arr = array (0, length arr - 2) [(i - (if i > index then 1 else 0), arr ! i) | i <- [0..length arr - 1], i /= index]

In this example, the deleteElement function takes an integer index and an array and returns a new array with the element at the given index removed. The array indices start at 0.

For example, if we have an array of integers [1, 2, 3, 4, 5] and we want to remove the element at index 2 (which is 3), we can call this function like this:

main :: IO ()
main = do
    let arr = listArray (0, 4) [1, 2, 3, 4, 5]
        newArr = deleteElement 2 arr
    print newArr -- Output: array (0, 3) [(0,1),(1,2),(2,4),(3,5)]

The resulting array will be [1, 2, 4, 5] or array (0, 3) [(0,1),(1,2),(2,4),(3,5)].