In playing with list_debug_topics/0 a little more I halted my top level, then restarted it and did list_debug_topics/0 again.
?- list_debug_topics.
---------------------------------------------
Debug Topic Activated To
---------------------------------------------
setting false []
listing(source) false []
read false []
clause_info false []
backtrace false []
true.
Is seems that as other code is consulted more topics can be added to the list. So if you don’t get the same list as I have listed, don’t be surprised.
In this next example I consulted the code from testinput.pl
?- list_debug_topics.
---------------------------------------------
Debug Topic Activated To
---------------------------------------------
setting false []
listing(source) false []
read false []
clause_info false []
backtrace false []
socket(proxy) false []
thread_pool(state) false []
thread_pool(current) false []
thread_pool false []
html(mailman) false []
http(header) false []
http(request) false []
obsolete false []
cookie false []
http(hook) false []
http(transfer_encoding) false []
http(cgi) false []
http_path false []
http(connection) false []
http(worker) false []
http(keep_alive) false []
http(server) false []
http(spawn) false []
http(error) true [user_error]
http(proxy) false []
http(send_request) false []
http(redirect) false []
http(open) false []
http(_498) false []
multipart(content) false []
multipart(bom) false []
post_request false []
post false []
true.
For some real working of examples using this see package HTTP
GitHub query
or see the file pengines.pl