We want to be able to develop a program interactively. This suggests that we will edit our program using one of the editors provided (such as vi, ex, gnu emacs or microemacs), enter Prolog, load our program, find a bug, exit Prolog and repeat.
This is clumsy, so we describe two methods that should aid interactive program development. In both cases, however, we must be aware of a problem in connection with consult/1.