- Documentation
- Reference manual
- Overview
- Getting started quickly
- The user's initialisation file
- Initialisation files and goals
- Command line options
- GNU Emacs Interface
- Online Help
- Command line history
- Reuse of top-level bindings
- Overview of the Debugger
- Compilation
- Environment Control (Prolog flags)
- An overview of hook predicates
- Automatic loading of libraries
- Packs: community add-ons
- Garbage Collection
- The SWI-Prolog syntax
- Rational trees (cyclic terms)
- Just-in-time clause indexing
- Wide character support
- System limits
- SWI-Prolog and 64-bit machines
- Overview
- Packages
- Reference manual
2.6 Online Help
SWI-Prolog provides an online help system that covers this manual. If
the XPCE graphics system is available, online help opens a graphical
window. Otherwise the documentation is shown in the Prolog console. The
help system is controlled by the predicates below. Note that this help
system only covers the core SWI-Prolog manual. The website12http://www.swi-prolog.org
provides an integrated manual that covers the core system as well as all
standard extension packages. It is possible to install the SWI-Prolog
website locally by cloning the website repository
git://www.swi-prolog.org/home/pl/git/plweb.git
and following the instructions in the README file.
- help
- Equivalent to
help(help/1). - help(+What)
- Show specified part of the manual. What is one of:
<Name>/<Arity> Give help on specified predicate <Name> Give help on named predicate with any arity or C interface function with that name <Section> Display specified section. Section numbers are dash-separated numbers: 2-3refers to section 2.3 of the manual. Section numbers are obtained using apropos/1.Examples:
?- help(assert).Give help on predicate assert ?- help(3-4).Display section 3.4 of the manual ?- help('PL_retry').Give help on interface function PL_retry() See also apropos/1 and the SWI-Prolog home page at http://www.swi-prolog.org, which provides a FAQ, an HTML version of the manual for online browsing, and HTML and PDF versions for downloading.
- apropos(+Pattern)
- Display all predicates, functions and sections that have Pattern
in their name or summary description. Lowercase letters in
Pattern also match a corresponding uppercase letter. Example:
?- apropos(file).Display predicates, functions and sections that have `file' (or `File', etc.) in their summary description. - explain(+ToExplain)
- Give an explanation on the given `object'. The argument may be any Prolog data object. If the argument is an atom, a term of the form Name/Arity or a term of the form Module:Name/Arity, explain/1 describes the predicate as well as possible references to it. See also gxref/0.
- explain(+ToExplain, -Explanation)
- Unify Explanation with an explanation for ToExplain. Backtracking yields further explanations.