Is it possible to trace through gap code?
Are there some useful commands to help debugging
gap routines? I found out about Backtrace in some
message on this forum, but couldn't find it
in the manual. Of course one can always interrupt
execution and inspect variables (very useful) and
after inserting enough ugly print statements in the
clean (but errant) gap code
one can eventually figure out what went wrong,
but then everything needs to be cleaned back up.
Maybe other users have come up with more
elegant ideas?

I guess in an ideal world only bug
free code would be written, and gap goes a long way
towards implementing mathematical algorithms in a
natural way, but with the innovative semantics of
list assingment I have managed to create some rather
subtle bugs. Even so, writing gap routines is in my experience far
less time consuming that using traditional programming
tools.

Peter Jipsen