:: [a] -> Int -> Maybe a package:base-compat

List index (subscript) operator, starting from 0. Returns Nothing if the index is out of bounds

>>> ['a', 'b', 'c'] !? 0
Just 'a'

>>> ['a', 'b', 'c'] !? 2
Just 'c'

>>> ['a', 'b', 'c'] !? 3
Nothing

>>> ['a', 'b', 'c'] !? (-1)
Nothing

This is the total variant of the partial !! operator. WARNING: This function takes linear time in the index.