User:Duplode/Apfelmus' loop for Control structures

Explain, step by step, what the  action in the final box note does, and in particular what is the role of the. Hints:
 * is an action analogous to, except that, instead of taking a newline-terminated series of characters from the standard input and making a  , it takes just a single character as soon as it is input.
 * If you have trouble with the control flow within, run it in GHCi to get a better feel of what it does.