Both the toplevel query/answer loop as the debugger abbreviate long
complex terms. They do this to avoid endless pages of output. In fact,
they write using write_term/3 which takes an option-list as argument.
The option list for answers printed by the Prolog toplevel is in the
toplevel_print_options and the one for the debugger is in
debugger_print_options. Initially both have the value given below:
?- current_prolog_flag(toplevel_print_options, X). X = [quoted(true), portray(true), max_depth(10), spacing(next_argument)].
max_depth(10) says anything nested more then 10 levels should
be written as
If the system prints an answer that is abbreviated and you want to see
it all, type w and the system will use plain write/1 for printing the
answer: (the user pressed w at the place the diagram says
[write]). Note the ; true. This is used to introduce
non-determinism that makes Prolog wait after the answer. If the
answer is deterministic, Prolog prints it with the default settings
and prompts for the next command.
?- atom_chars(goodbye_prolog, X) ; true. X = [g, o, o, d, b, y, e, '_', p|...] [write] X = [g, o, o, d, b, y, e, '_', p, r, o, l, o, g]
Use the p command to get the default behaviour.
?- set_prolog_flag(toplevel_print_options, [quoted(true), portray(true)]).