Using listing/N and such

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The built-in predicate listing/0,1,2 from library(listing) is used to list the contents of the database. It is more commonly thought of as listing facts, predicates, clauses and filtering based on module or predicate/fact name.

Using listing/0 will list the contents of the global user module. (ref)


listing/0 is the same as

user:listing.

or

listing(user:_).

listing/1 can be used to show the same predicate in different modules.

Note: The predicate group is from my own code, so this is exact predicate will not work for you.

?- listing(group).
Example
?- listing(group).
rfc5234:group([40|T0], T, [40|A], B) :-
    'cwsp*'(T0, T1, A, C),
    alternation(T1, T2, C, D),
    'cwsp*'(T2, [41|T], D, E),
    E=[41|B].

rfc5234_format_preserving:group(Structure, [40|A], B) :-
    'cwsp*'(Before, A, C),
    alternation(Alternation, C, D),
    'cwsp*'(After, D, E),
    E=[41|F],
    group_structure(Before,
                    After,
                    Alternation,
                    Structure),
    B=F.

rfc5234_structure_preserving:group(Structure, [40|A], B) :-
    'cwsp*'(_, A, C),
    alternation(Alternation, C, D),
    'cwsp*'(_, D, E),
    E=[41|F],
    group_structure(Alternation, Structure),
    B=F.

true.

To see the list of current modules loaded use current_module/1.

?- current_module(M).
Example
?- current_module(M).
M = sandbox ;
M = read_util ;
M = error ;
M = qsave ;
M = swi_option ;
M = prolog_listing ;
M = predopts_analysis ;
M = prolog_history ;
M = prolog_stack ;
M = predicate_options ;
M = prolog ;
M = shlib ;
M = pce_swi_hooks ;
M = prolog_clause ;
M = lists ;
M = arithmetic ;
M = prolog_debug ;
M = settings ;
M = prolog_system_predicate_options ;
M = ansi_term ;
M = prolog_operator ;
M = pce_expansion ;
M = listing ;
M = win_menu ;
M = link_xpce ;
M = base32 ;
M = system ;
M = prolog_source ;
M = user ;
false.

Different modules can be selected for use with listing/0,1,2 using either

<module>:listing.

or

listing(<module>:_).

To see the list of current predicates loaded use current_predicate/1.

Examples
?- aggregate_all(count,current_predicate(_),Count).
Count = 1330.

?- current_predicate(append/2).
true.

?- current_predicate(append/N).
N = 1 ;
N = 2 ;
false.

?- current_predicate(lists:Name).
Name = prefix/2 ;
Name = must_be/2 ;
Name = remove_dup_keys/2 ;
Name = numlist_/3 ;
Name = remove_same_key/3 ;
Name = max_list/3 ;
Name = select/3 ;
Name = subset/2 ;
Name = is_set/1 ;
Name = intersection/3 ;
Name = nth_gen/5 ;
Name = '$autoload'/3 ;
Name = find_nth0/4 ;
Name = append/2 ;
Name = min_list/2 ;
Name = sum_list/2 ;
Name = min_member/2 ;
Name = reverse/4 ;
Name = flatten/2 ;
Name = member_/3 ;
Name = reverse/2 ;
Name = proper_length/2 ;
Name = select3_/4 ;
Name = select/4 ;
Name = flatten/3 ;
Name = min_member_/3 ;
Name = nth0/3 ;
Name = sort/4 ;
Name = nextto/3 ;
Name = nth1/4 ;
Name = number_list/3 ;
Name = member/2 ;
Name = min_list/3 ;
Name = sum_list/3 ;
Name = max_member_/3 ;
Name = append/3 ;
Name = subtract/3 ;
Name = union/3 ;
Name = list_to_set/2 ;
Name = generate_nth/5 ;
Name = last_/3 ;
Name = numlist/3 ;
Name = max_list/2 ;
Name = nth0_det/3 ;
Name = perm/2 ;
Name = max_member/2 ;
Name = nth1/3 ;
Name = permutation/2 ;
Name = append_/2 ;
Name = same_length/2 ;
Name = select4_/4 ;
Name = last/2 ;
Name = pairs_keys/2 ;
Name = delete/3 ;
Name = selectchk/4 ;
Name = succ/2 ;
Name = selectchk/3 ;
Name = nth0/4 ;
false.


Different predicate/fact names can be selected using either

<module>:listing(<predicate indicator>).

or

listing(<module>:<predicate indicator>).
Examples
?- listing(lists:append/2).
append(ListOfLists, List) :-
    must_be(list, ListOfLists),
    append_(ListOfLists, List).

true.

?- lists:listing(append/2).
append(ListOfLists, List) :-
    must_be(list, ListOfLists),
    append_(ListOfLists, List).

true.

?- lists:listing(append/N).
append(ListOfLists, List) :-
    must_be(list, ListOfLists),
    append_(ListOfLists, List).

append([], L, L).
append([H|T], L, [H|R]) :-
    append(T, L, R).

true.

Predicates have properties which can be accessed with predicate_property/2.

Examples
?- aggregate_all(count,predicate_property(H,multifile),Count).
Count = 23.

?- aggregate_all(count,predicate_property(H,imported_from(F)),Count).
Count = 117.

?- predicate_property(H,multifile).
H = expand_query(_9774, _9776, _9778, _9780) ;
H = prolog_load_file(_10446, _10448) ;
H = portray(_11114) ;
H = pce_pre_expansion_hook(_11780, _11782) ;
H = prolog_file_type(_12448, _12450) ;
H = prolog_exception_hook(_13116, _13118, _13120, _13122) ;
H = expand_answer(_13788, _13790) ;
H = resource(_14456, _14458, _14460) ;
H = message_property(_15126, _15128) ;
H = url_path(_15794, _15796) ;
H = term_expansion(_16462, _16464, _16466, _16468) ;
H = message_hook(_17134, _17136, _17138) ;
H = prolog_clause_name(_17804, _17806) ;
H = exception(_18472, _18474, _18476) ;
H = library_directory(_19142) ;
H = prolog_list_goal(_19808) ;
H = goal_expansion(_20474, _20476, _20478, _20480) ;
H = prolog_predicate_name(_21146, _21148) ;
H = term_expansion(_21814, _21816) ;
H = pce_post_expansion_hook(_22482, _22484) ;
H = file_search_path(_23150, _23152) ;
H = goal_expansion(_23818, _23820) ;
H = resource(_24486, _24488) ;
false.

?- predicate_property(PI,number_of_rules(C)),C > 1.
PI = subset(_646, _648),
C = 2 ;
PI = absolute_file_name(_1694, _1696, _1698),
C = 2 ;
PI = print_message(_2744, _2746),
C = 2 ;
PI = portray(_3792),
C = 4 ;
PI = spy(_4838),
C = 5 ;
PI = prolog_file_type(_5884, _5886),
C = 2 ;
PI = stream_position_data(_6932, _6934, _6936),
C = 2 ;
PI = absolute_file_name(_7982, _7984),
C = 3 ;
PI = intersection(_9030, _9032, _9034),
C = 3 ;
PI = union(_10080, _10082, _10084),
C = 3 ;
PI = module_property(_11130, _11132),
C = 3 ;
PI = current_predicate(_12178, _12180),
C = 4 ;
PI = message_hook(_13226, _13228, _13230),
C = 10 ;
PI = source_file_property(_14276, _14278),
C = 2 ;
PI = prolog_list_goal(_15324),
C = 2 ;
PI = subtract(_16370, _16372, _16374),
C = 3 ;
PI = prolog_predicate_name(_17420, _17422),
C = 2 ;
PI = file_search_path(_18468, _18470),
C = 15 ;
PI = prolog_load_context(_19516, _19518),
C = 11 ;
PI = aggregate_all(_20564, _20566, _20568),
C = 8 ;
PI = flag(_21614, _21616, _21618),
C = 2 ;
PI = list_predicates(_22664),
C = 2 ;
false.

?- predicate_property(append(A,B,C),P).
P = interpreted ;
P = visible ;
P = static ;
P = imported_from(lists) ;
P = file('c:/program files/swipl/library/lists.pl') ;
P = line_count(123) ;
P = nodebug ;
P = number_of_clauses(2) ;
P = number_of_rules(1) ;
P = last_modified_generation(5699) ;
P = defined ;
P = size(480).

NB append/3 will return a result but most likely not the one you expect.
If you see imported_from(yall) then this is probably not what you want.
In other words don’t use the predicate indicator notation of <name>/<arity>,
use a template form <name>(<args>)

Example
?- predicate_property(append/3,P).
P = interpreted ;
P = visible ;
P = static ;
P = imported_from(yall) ;
P = transparent ;
P =  (meta_predicate? / 0) ;
P = file('c:/program files/swipl/library/yall.pl') ;
P = line_count(275) ;
P = number_of_clauses(1) ;
P = number_of_rules(1) ;
P = last_modified_generation(5613) ;
P = defined ;
P = size(384).

TODO: Create example with property wrapped. See: prolog_wrap.pl – Wrapping predicates


Modules have properties which can be accessed with module_property/2.

Examples
?- module_property(user,Property).
Property = class(user) ;
Property = exports([]) ;
Property = exported_operators([]) ;
Property = size(17296) ;
Property = program_size(5184) ;
Property = last_modified_generation(7106).

?- module_property(Module,file(F)).
Module = pce_swi_hooks,
F = 'c:/program files/swipl/xpce/prolog/lib/swi_hooks.pl' ;
Module = prolog_stack,
F = 'c:/program files/swipl/library/prolog_stack.pl' ;
Module = prolog_clause,
F = 'c:/program files/swipl/library/prolog_clause.pl' ;
Module = predicate_options,
F = 'c:/program files/swipl/library/predicate_options.pl' ;
Module = read_util,
F = 'c:/program files/swipl/library/readutil.pl' ;
Module = win_menu,
F = 'c:/program files/swipl/library/win_menu.pl' ;
Module = swi_option,
F = 'c:/program files/swipl/library/option.pl' ;
Module = prolog_listing,
F = 'c:/program files/swipl/library/listing.pl' ;
Module = prolog_operator,
F = 'c:/program files/swipl/library/operators.pl' ;
Module = link_xpce,
F = 'c:/program files/swipl/swipl-win.rc' ;
Module = prolog_system_predicate_options,
F = 'c:/program files/swipl/library/dialect/swi/syspred_options.pl' ;
Module = aggregate,
F = 'c:/program files/swipl/library/aggregate.pl' ;
Module = lists,
F = 'c:/program files/swipl/library/lists.pl' ;
Module = prolog_source,
F = 'c:/program files/swipl/library/prolog_source.pl' ;
Module = shlib,
F = 'c:/program files/swipl/library/shlib.pl' ;
Module = error,
F = 'c:/program files/swipl/library/error.pl' ;
Module = base32,
F = 'c:/program files/swipl/library/base32.pl' ;
Module = settings,
F = 'c:/program files/swipl/library/settings.pl' ;
Module = arithmetic,
F = 'c:/program files/swipl/library/arithmetic.pl' ;
Module = prolog_debug,
F = 'c:/program files/swipl/library/debug.pl' ;
Module = ansi_term,
F = 'c:/program files/swipl/library/ansi_term.pl' ;
Module = prolog_history,
F = 'c:/program files/swipl/library/prolog_history.pl' ;
false.

?- module_property(Module,class(Class)).
Module = pce_swi_hooks,
Class = development ;
Module = prolog_stack,
Class = library ;
Module = prolog_clause,
Class = library ;
Module = predicate_options,
Class = library ;
Module = sandbox,
Class = user ;
Module = read_util,
Class = library ;
Module = listing,
Class = user ;
Module = prolog,
Class = user ;
Module = win_menu,
Class = library ;
Module = swi_option,
Class = library ;
Module = prolog_listing,
Class = library ;
Module = pce_expansion,
Class = user ;
Module = prolog_operator,
Class = library ;
Module = link_xpce,
Class = library ;
Module = prolog_system_predicate_options,
Class = library ;
Module = aggregate,
Class = library ;
Module = lists,
Class = library ;
Module = prolog_source,
Class = library ;
Module = shlib,
Class = library ;
Module = error,
Class = library ;
Module = qsave,
Class = user ;
Module = Class,
Class = system ;
Module = base32,
Class = library ;
Module = settings,
Class = library ;
Module = arithmetic,
Class = library ;
Module = prolog_debug,
Class = library ;
Module = ansi_term,
Class = library ;
Module = predopts_analysis,
Class = user ;
Module = prolog_history,
Class = library ;
Module = Class, Class = user ;
false.

Some of the Prolog flags can be set per module.

Example
?- user:current_prolog_flag(double_quotes,Value).
Value = string.

?- user:set_prolog_flag(double_quotes,codes).
true.

?- user:current_prolog_flag(double_quotes,Value).
Value = codes.

?- current_module(M),current_prolog_flag(M:double_quotes,Value).
M = pce_swi_hooks,
Value = string ;
M = prolog_stack,
Value = string ;
M = prolog_clause,
Value = string ;
M = predicate_options,
Value = string ;
M = read_util,
Value = string ;
M = prolog,
Value = string ;
M = win_menu,
Value = string ;
M = link_xpce,
Value = string ;
M = prolog_system_predicate_options,
Value = string ;
M = shlib,
Value = string ;
M = qsave,
Value = string ;
M = system,
Value = string ;
M = base32,
Value = string ;
M = ansi_term,
Value = string ;
M = predopts_analysis,
Value = string ;
M = prolog_history,
Value = string ;
M = user,
Value = codes ;
false.

Sometimes the output is very long and scrolls off the screen. To save the output to a file use with_output_to_file/2.

Example
?- use_module(library(fileutils)).
true.

% Yes you can load a module from top.

?- with_output_to_file('C:/Users/Eric/Documents/append.listing.pl',listing(append)).
true.

append.listing.pl

lists:append(ListOfLists, List) :-
    must_be(list, ListOfLists),
    append_(ListOfLists, List).

lists:append([], L, L).
lists:append([H|T], L, [H|R]) :-
    append(T, L, R).

%   Foreign: system:append/1

Note: This uses package fileutils which must be installed.

How to install package fileutils
% Check to make sure it is not already installed.

?- pack_list_installed.
Installed packages (6):

i edcg@0.9.1.2              - Extended DCG
i func@0.4.2                - Function application and composition
i function_expansion@0.1.2  - Help for writing function-like macros
i list_util@0.13.0          - Predicates for working with lists
i quickcheck@0.3.0          - QuickCheck randomized testing
i sldnfdraw@1.61            - SLDNF Draw is a Prolog program that draws SLDNF Trees in LaTeX
true.

% Check to make sure it is available.

?- pack_search(fileutils).
% Contacting server at https://www.swi-prolog.org/pack/query ... ok
p fileutils@0.3.5           - Utilities for reading, writing and finding files
true.

% Install package fileutils

?- pack_install(fileutils).
% Contacting server at https://www.swi-prolog.org/pack/query ... ok
Install fileutils@0.3.5 from https://raw.githubusercontent.com/samer--/prolog/master/fileutils/release/fileutils-0.3.5.tgz Y/n? 
% Contacting server at https://www.swi-prolog.org/pack/query ...
 ok
% "fileutils-0.3.5.tgz" was downloaded 10 times
Package:                fileutils
Title:                  Utilities for reading, writing and finding files
Installed version:      0.3.5
Author:                 Samer Abdallah <s.abdallah@ucl.ac.uk>
Download URL:           https://raw.githubusercontent.com/samer--/prolog/master/fileutils/release/fileutils-0.3.5.tgz
Install "fileutils-0.3.5.tgz" (20,606 bytes) Y/n? 
true.

% Check to see it was installed

?- pack_list_installed.
Installed packages (7):

i edcg@0.9.1.2              - Extended DCG
i fileutils@0.3.5           - Utilities for reading, writing and finding files
i func@0.4.2                - Function application and composition
i function_expansion@0.1.2  - Help for writing function-like macros
i list_util@0.13.0          - Predicates for working with lists
i quickcheck@0.3.0          - QuickCheck randomized testing
i sldnfdraw@1.61            - SLDNF Draw is a Prolog program that draws SLDNF Trees in LaTeX
true.

Most libraries are located in the library directory under current_prolog_flag(home,Value)., e.g.

?- current_prolog_flag(home,Value).
Value = 'c:/program files/swipl'.

C:/program files/swipl/library

however some libraries are not at the root level of the library directory but in a subdirectory. One popular library as such is library\dcg\basics.pl.

dcg\basics can be loaded with

use_module(library(dcg/basics)).

then the module name can be found using current_module/1, e.g. current_module(M). which shows that the module name for dcg/basics is dcg_basics.


With SWI-Prolog - unit test using

:- begin_tests(<name>).  
...
:- end_tests(<name>).

the section (test box) is converted into a module with the name plunit_<name>. The test in the section are proper predicates that can be listed using the constructed module name.


TODO: Add example based on SO Q&A


Note: Some editors have these types of queries built-in. As I use VSC (Visual Studio Code) I have to rely on using these instead.