SWI-Prolog -- portray

Documentation
- Reference manual
  - The SWI-Prolog library
    - library(listing): List programs and pretty print clauses
- Packages

Availability::- use_module(library(listing)).(can be autoloaded)

[det]portray_clause(+Clause)

[det]portray_clause(+Out:stream, +Clause)

[det]portray_clause(+Out:stream, +Clause, +Options)

Portray‘Clause’on the current output stream. Layout of the clause is to our best standards. Deals with control structures 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.

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:

variable_names(+Bindings): See above and write_term/2.
indent(+Columns): Left margin used for the clause. Default 0.
module(+Module): Module used to determine whether a goal resolves to a meta predicate. Default user.