For sure you've been noticed that function must be pure... or watch there is a place for side effect. Yes and we will tell about this in that section - Computation priority
A real example of queue priority - people awaiting medical treatment hospital, extreme emergency cases will have the highest priority and move on the start of the queue less significant at the end.
The main of the reason for creating Computation priority was that side effects:
- Letting go first pure functions
- Following consistent state of application