Heeding warnings

When we load our first implementation into the ECLiPSe system, it is quite possible that we find a number of error and warning messages. Errors will usually be caused by simple syntax problems, by forgetting to define some predicate or by not importing a module where it is required. These errors are typically easy to fix once we understand which part of the program is responsible.

It is tempting to ignore warnings in order to get the code running as quickly as possible. That would be a big mistake. We should eliminate all warnings about singleton variables and missing predicate definitions before continuing. Not only will this lead to the detection of problems in the code at this point, we will also immediately see if new warnings are introduced when we change some part of the program.