Suppose that the file foobar.pl in the current working
directory contains the following minimal knowledgebase:
foo(bar).
foo(baz).
frobozz.
If I start swi-prolog (by running swipl at the command), and immediately run
?- [foobar].
% foobar compiled 0.00 sec, 4 clauses
true.
?- listing.
...the contents of foobar are lost in a sea of >100 lines of unrelated output.
How can I limit listing's output to foobar?
Alternatively, how can I limit it to contents of those knowledgebases I have explicitly consulted?
I did look at the docs for listing/1 and listing/0, but I could not find anything helpful:
listing/1 List predicates specified by Pred. Pred may be a predicate name (atom), which lists all predicates with this name, regardless of their arity. It can also be a predicate indicator (/ or //), possibly qualified with a module. For example: ?- listing(lists:member/2)..
A listing is produced by enumerating the clauses of the predicate using clause/2 and printing each clause using portray_clause/1. This implies that the variable names are generated (A, B, ... ) and the layout is defined by rules in portray_clause/1.
listing/0 List all predicates from the calling module using listing/1. For example, ?- listing. lists clauses in the default user module and ?- lists:listing. lists the clauses in the module lists.
Of course, I did try the following useless idea:
?- foobar:listing.
true.
You can load the contents of a plain Prolog file into a module easily. For example:
?- fb:consult(foobar).
true
And then call:
?- fb:listing.
foo(bar).
foo(baz).
frobozz.
true.
Or list just a specific predicate:
?- fb:listing(foo/1).
foo(bar).
foo(baz).
true.