listing.pl -- List programs and pretty print clauses

This module implements listing code from the internal representation in a human readable format.

• listing/0 lists a module.
• listing/1 lists a predicate or matching clause
• portray_clause/2 pretty-prints a clause-term

Layout can be customized using library(settings). The effective settings can be listed using list_settings/1 as illustrated below. Settings can be changed using set_setting/2.

?- list_settings(listing).
========================================================================
Name                      Value (*=modified) Comment
========================================================================
listing:body_indentation  8              Indentation used goals in the body
listing:tab_distance      8              Distance between tab-stops.
...

To be done

- More settings, support Coding Guidelines for Prolog and make the suggestions there the default.

- Provide persistent user customization

 listing

Lists all predicates defined in the calling module. Imported predicates are not listed. To list the content of the module mymodule, use:

?- mymodule:listing.

 listing(:What)

List matching clauses. What is either a plain specification or a list of specifications. Plain specifications are:

• Predicate indicator (Name/Arity or Name//Arity) Lists the indicated predicate. This also outputs relevant declarations, such as multifile/1 or dynamic/1.
• A Head term. In this case, only clauses whose head unify with Head are listed. This is illustrated in the query below that only lists the first clause of append/3.

  ?- listing(append([], _, _)).
  lists:append([], A, A).

 portray_clause(+Clause) is det

 portray_clause(+Out:stream, +Clause) is det

 portray_clause(+Out:stream, +Clause, +Options) is det

Portray `Clause' on the current output stream. Layout of the clause is to our best standards. As the actual variable names are not available we use A, B, ... Deals with ';', '|', '->' and calls via meta-call predicates as determined using the predicate property meta_predicate. If Clause contains attributed variables, these are treated as normal variables.

If Options is provided, the option-list is passed to write_term/3 that does the final writing of arguments.

 portray_clause(+Clause) is det

 portray_clause(+Out:stream, +Clause) is det

 portray_clause(+Out:stream, +Clause, +Options) is det

Portray `Clause' on the current output stream. Layout of the clause is to our best standards. As the actual variable names are not available we use A, B, ... Deals with ';', '|', '->' and calls via meta-call predicates as determined using the predicate property meta_predicate. If Clause contains attributed variables, these are treated as normal variables.

If Options is provided, the option-list is passed to write_term/3 that does the final writing of arguments.

 portray_clause(+Clause) is det

 portray_clause(+Out:stream, +Clause) is det

 portray_clause(+Out:stream, +Clause, +Options) is det

Portray `Clause' on the current output stream. Layout of the clause is to our best standards. As the actual variable names are not available we use A, B, ... Deals with ';', '|', '->' and calls via meta-call predicates as determined using the predicate property meta_predicate. If Clause contains attributed variables, these are treated as normal variables.

If Options is provided, the option-list is passed to write_term/3 that does the final writing of arguments.