Sorry, what I meant is that when the application rerenders (digesting changes that have been made) it will re-evaluate the function to check if the result has changed.
Polling the function for changes, contrast with how e.g. knockout.js pushes changes. (I could be wrong, please let me know if my understanding's not reality)
Ah, yeah I think you've got it right. I thought you meant polling as in it checked every X milliseconds for changes.