Problem Statement

Demonstrate any means your language has to prevent the modification of values, or to create objects that cannot be modified after they have been created.

Let's start with the solution:

user> (def d [1 2 3 4 5]) ; immutable vector
#'user/d
user> (assoc d 3 7)
[1 2 3 7 5]
user> d
[1 2 3 4 5]