Does GAP always complete its task before returning the prompt?

Question

In investigating a certain problem, I let a GAP program run for a few days. It eventually terminated and presented me the prompt again. Does this guarantee that it ran the previously entered code or could something else have happened? If something else could have happened, then what?

Answer 1

First, I find the word "terminated" a bit misleading here. In this situation I would say that your program completed and presented the prompt. "Termination" for me would mean some abnormal scenario.

Second, GAP works in "read-evaluate-print" loop, as documented in the Chapter Main Loop and Break Loop of the GAP manual. If you type an input, GAP reads it, then evaluates it, and then shows the result. Thus, if you get the next GAP prompt, then the previous command has been evaluated.

ALso, you may be interested to use LogTo (see here) to log the GAP session into a file. For example, if you return to the session after several days and the server has been restarted, then it will be lost - by the log file will still be available.