If it's a partial read that requires to track state, then yes. If it's a somehow self-contained read operation that returns a result, while it has side effects

If it's a partial read that requires to track state, then yes. If it's a somehow self-contained read operation that returns a result, while it has side effects (I/O), it may not necessarily have to mutate variables in your program (e.g: load a small file into string variable, make a HTTP response and return the body, etc).