This module implements listing code from the internal representation in a human readable format.
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 4 Indentation used goals in the body listing:tab_distance 0 Distance between tab-stops. ...
mymodule, use one of the calls below.
?- mymodule:listing. ?- listing(mymodule:_).
//Arity) Lists 
the indicated predicate. This also outputs relevant
declarations, such as multifile/1 
or dynamic/1.
?- listing(append([], _, _)). lists:append([], L, L).
The following options are defined:
source (default) or generated. If source, 
for each clause that is associated to a source location the system tries 
to restore the original variable names. This may fail if macro expansion 
is not reversible or the term cannot be read due to different operator 
declarations. In that case variable names are generated.
true (default false), extract the lines 
from the source files that produced the clauses, i.e., list the original 
source text rather than the decompiled clauses. Each set of 
contiguous clauses is preceded by a comment that indicates the file and 
line of origin. Clauses that cannot be related to source code are 
decompiled where the comment indicates the decompiled state. This is 
notably practical for collecting the state of multifile 
predicates. For example:
?- listing(file_search_path, [source(true)]).
Variable names are by default generated using numbervars/4 
using the option singletons(true). This names the variables A, B, 
... and the singletons _. Variables can be named explicitly 
by binding them to a term '$VAR'(Name), where Name 
is an atom denoting a valid variable name (see the option numbervars(true) 
from
write_term/2) as 
well as by using the variable_names(Bindings) option from write_term/2.
Options processed in addition to write_term/2 options:
0.
user.