At one time or another, you will get caught in an infinite loop. Here are some particularly simple examples of programs which never terminate.
> do od; > for i from 1 to 10 do > if (i=10) then > i:=1; > fi; > lprint('i = ', i); > od;
To interrupt the computation, type the <control-c> sequence (press the c key while simultaneously holding down the control (or ctrl) key).