1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        J.Wielemaker@vu.nl
    5    WWW:           http://www.swi-prolog.org
    6    Copyright (c)  1997-2025, University of Amsterdam
    7                              VU University Amsterdam
    8                              CWI, Amsterdam
    9                              SWI-Prolog Solutions b.v.
   10    All rights reserved.
   11
   12    Redistribution and use in source and binary forms, with or without
   13    modification, are permitted provided that the following conditions
   14    are met:
   15
   16    1. Redistributions of source code must retain the above copyright
   17       notice, this list of conditions and the following disclaimer.
   18
   19    2. Redistributions in binary form must reproduce the above copyright
   20       notice, this list of conditions and the following disclaimer in
   21       the documentation and/or other materials provided with the
   22       distribution.
   23
   24    THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   25    "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   26    LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
   27    FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
   28    COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
   29    INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
   30    BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
   31    LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
   32    CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
   34    ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   35    POSSIBILITY OF SUCH DAMAGE.
   36*/
   37
   38:- module('$messages',
   39          [ print_message/2,            % +Kind, +Term
   40            print_message_lines/3,      % +Stream, +Prefix, +Lines
   41            message_to_string/2         % +Term, -String
   42          ]).   43
   44:- multifile
   45    prolog:message//1,              % entire message
   46    prolog:error_message//1,        % 1-st argument of error term
   47    prolog:message_context//1,      % Context of error messages
   48    prolog:deprecated//1,	    % Deprecated features
   49    prolog:message_location//1,     % (File) location of error messages
   50    prolog:message_line_element/2,  % Extend printing
   51    prolog:message_action/2.        % Side effects (broadcast)
   52:- '$hide'((
   53    prolog:message//1,
   54    prolog:error_message//1,
   55    prolog:message_context//1,
   56    prolog:deprecated//1,
   57    prolog:message_location//1,
   58    prolog:message_line_element/2)).   59% Lang, Term versions
   60:- multifile
   61    prolog:message//2,              % entire message
   62    prolog:error_message//2,        % 1-st argument of error term
   63    prolog:message_context//2,      % Context of error messages
   64    prolog:message_location//2,	    % (File) location of error messages
   65    prolog:deprecated//2.	    % Deprecated features
   66:- '$hide'((
   67    prolog:message//2,
   68    prolog:error_message//2,
   69    prolog:message_context//2,
   70    prolog:deprecated//2,
   71    prolog:message_location//2)).   72
   73:- discontiguous
   74    prolog_message/3.   75
   76:- public
   77    translate_message//1,           % +Message (deprecated)
   78    prolog:translate_message//1.    % +Message
   79
   80:- create_prolog_flag(message_context, [thread], []).

 translate_message(+Term)// is det

Translate a message Term into message lines. The produced lines is a list of

nl

Emit a newline

Fmt - Args

Emit the result of format(Fmt, Args)

Fmt

Emit the result of format(Fmt)

ansi(Code, Fmt, Args)

Use ansi_format/3 for color output.

flush

Used only as last element of the list. Simply flush the output instead of producing a final newline.

at_same_line

Start the messages at the same line (instead of using ~N)

deprecated

- Use code for message translation should call translate_message//1.

  104prolog:translate_message(Term) -->
  105    translate_message(Term).

 translate_message(+Term)// is det

Translate a message term into message lines. This version may be called from user and library definitions for message translation.

  112translate_message(Term) -->
  113    { nonvar(Term) },
  114    (   { message_lang(Lang) },
  115        prolog:message(Lang, Term)
  116    ;   prolog:message(Term)
  117    ),
  118    !.
  119translate_message(Term) -->
  120    { nonvar(Term) },
  121    translate_message2(Term),
  122    !.
  123translate_message(Term) -->
  124    { nonvar(Term),
  125      Term = error(_, _)
  126    },
  127    [ 'Unknown exception: ~p'-[Term] ].
  128translate_message(Term) -->
  129    [ 'Unknown message: ~p'-[Term] ].
  130
  131translate_message2(Term) -->
  132    prolog_message(Term).
  133translate_message2(error(resource_error(stack), Context)) -->
  134    !,
  135    out_of_stack(Context).
  136translate_message2(error(resource_error(tripwire(Wire, Context)), _)) -->
  137    !,
  138    tripwire_message(Wire, Context).
  139translate_message2(error(existence_error(reset, Ball), SWI)) -->
  140    swi_location(SWI),
  141    tabling_existence_error(Ball, SWI).
  142translate_message2(error(ISO, SWI)) -->
  143    swi_location(SWI),
  144    term_message(ISO),
  145    swi_extra(SWI).
  146translate_message2(unwind(Term)) -->
  147    unwind_message(Term).
  148translate_message2(message_lines(Lines), L, T) :- % deal with old C-warning()
  149    make_message_lines(Lines, L, T).
  150translate_message2(format(Fmt, Args)) -->
  151    [ Fmt-Args ].
  152
  153make_message_lines([], T, T) :- !.
  154make_message_lines([Last],  ['~w'-[Last]|T], T) :- !.
  155make_message_lines([L0|LT], ['~w'-[L0],nl|T0], T) :-
  156    make_message_lines(LT, T0, T).

 term_message(+Term)//

Deal with the formal argument of error(Format, ImplDefined) exception terms. The ImplDefined argument is handled by swi_location//2.

  164:- public term_message//1.  165term_message(Term) -->
  166    {var(Term)},
  167    !,
  168    [ 'Unknown error term: ~p'-[Term] ].
  169term_message(Term) -->
  170    { message_lang(Lang) },
  171    prolog:error_message(Lang, Term),
  172    !.
  173term_message(Term) -->
  174    prolog:error_message(Term),
  175    !.
  176term_message(Term) -->
  177    iso_message(Term).
  178term_message(Term) -->
  179    swi_message(Term).
  180term_message(Term) -->
  181    [ 'Unknown error term: ~p'-[Term] ].
  182
  183iso_message(resource_error(c_stack)) -->
  184    out_of_c_stack.
  185iso_message(resource_error(Missing)) -->
  186    [ 'Not enough resources: ~w'-[Missing] ].
  187iso_message(type_error(evaluable, Actual)) -->
  188    { callable(Actual) },
  189    [ 'Arithmetic: `~p'' is not a function'-[Actual] ].
  190iso_message(type_error(free_of_attvar, Actual)) -->
  191    [ 'Type error: `~W'' contains attributed variables'-
  192      [Actual,[portray(true), attributes(portray)]] ].
  193iso_message(type_error(Expected, Actual)) -->
  194    [ 'Type error: `~w'' expected, found `~p'''-[Expected, Actual] ],
  195    type_error_comment(Expected, Actual).
  196iso_message(domain_error(Domain, Actual)) -->
  197    [ 'Domain error: '-[] ], domain(Domain),
  198    [ ' expected, found `~p'''-[Actual] ].
  199iso_message(instantiation_error) -->
  200    [ 'Arguments are not sufficiently instantiated' ].
  201iso_message(uninstantiation_error(Var)) -->
  202    [ 'Uninstantiated argument expected, found ~p'-[Var] ].
  203iso_message(representation_error(What)) -->
  204    [ 'Cannot represent due to `~w'''-[What] ].
  205iso_message(permission_error(Action, Type, Object)) -->
  206    permission_error(Action, Type, Object).
  207iso_message(evaluation_error(Which)) -->
  208    [ 'Arithmetic: evaluation error: `~p'''-[Which] ].
  209iso_message(existence_error(procedure, Proc)) -->
  210    [ 'Unknown procedure: ~q'-[Proc] ],
  211    unknown_proc_msg(Proc).
  212iso_message(existence_error(answer_variable, Var)) -->
  213    [ '$~w was not bound by a previous query'-[Var] ].
  214iso_message(existence_error(matching_rule, Goal)) -->
  215    [ 'No rule matches ~p'-[Goal] ].
  216iso_message(existence_error(Type, Object)) -->
  217    [ '~w `~p'' does not exist'-[Type, Object] ].
  218iso_message(existence_error(export, PI, module(M))) --> % not ISO
  219    [ 'Module ', ansi(code, '~q', [M]), ' does not export ',
  220      ansi(code, '~q', [PI]) ].
  221iso_message(existence_error(Type, Object, In)) --> % not ISO
  222    [ '~w `~p'' does not exist in ~p'-[Type, Object, In] ].
  223iso_message(busy(Type, Object)) -->
  224    [ '~w `~p'' is busy'-[Type, Object] ].
  225iso_message(syntax_error(swi_backslash_newline)) -->
  226    [ 'Deprecated: ... \\<newline><white>*.  Use \\c' ].
  227iso_message(syntax_error(warning_var_tag)) -->
  228    [ 'Deprecated: dict with unbound tag (_{...}).  Mapped to #{...}.' ].
  229iso_message(syntax_error(var_tag)) -->
  230    [ 'Syntax error: dict syntax with unbound tag (_{...}).' ].
  231iso_message(syntax_error(Id)) -->
  232    [ 'Syntax error: ' ],
  233    syntax_error(Id).
  234iso_message(occurs_check(Var, In)) -->
  235    [ 'Cannot unify ~p with ~p: would create an infinite tree'-[Var, In] ].

 permission_error(Action, Type, Object)//

Translate permission errors. Most follow te pattern "No permission to Action Type Object", but some are a bit different.

  242permission_error(Action, built_in_procedure, Pred) -->
  243    { user_predicate_indicator(Pred, PI)
  244    },
  245    [ 'No permission to ~w built-in predicate `~p'''-[Action, PI] ],
  246    (   {Action \== export}
  247    ->  [ nl,
  248          'Use :- redefine_system_predicate(+Head) if redefinition is intended'
  249        ]
  250    ;   []
  251    ).
  252permission_error(import_into(Dest), procedure, Pred) -->
  253    [ 'No permission to import ~p into ~w'-[Pred, Dest] ].
  254permission_error(Action, static_procedure, Proc) -->
  255    [ 'No permission to ~w static procedure `~p'''-[Action, Proc] ],
  256    defined_definition('Defined', Proc).
  257permission_error(input, stream, Stream) -->
  258    [ 'No permission to read from output stream `~p'''-[Stream] ].
  259permission_error(output, stream, Stream) -->
  260    [ 'No permission to write to input stream `~p'''-[Stream] ].
  261permission_error(input, text_stream, Stream) -->
  262    [ 'No permission to read bytes from TEXT stream `~p'''-[Stream] ].
  263permission_error(output, text_stream, Stream) -->
  264    [ 'No permission to write bytes to TEXT stream `~p'''-[Stream] ].
  265permission_error(input, binary_stream, Stream) -->
  266    [ 'No permission to read characters from binary stream `~p'''-[Stream] ].
  267permission_error(output, binary_stream, Stream) -->
  268    [ 'No permission to write characters to binary stream `~p'''-[Stream] ].
  269permission_error(open, source_sink, alias(Alias)) -->
  270    [ 'No permission to reuse alias "~p": already taken'-[Alias] ].
  271permission_error(tnot, non_tabled_procedure, Pred) -->
  272    [ 'The argument of tnot/1 is not tabled: ~p'-[Pred] ].
  273permission_error(assert, procedure, Pred) -->
  274    { '$pi_head'(Pred, Head),
  275      predicate_property(Head, ssu)
  276    },
  277    [ '~p: an SSU (Head => Body) predicate cannot have normal Prolog clauses'-
  278      [Pred] ].
  279permission_error(Action, Type, Object) -->
  280    [ 'No permission to ~w ~w `~p'''-[Action, Type, Object] ].
  281
  282
  283unknown_proc_msg(_:(^)/2) -->
  284    !,
  285    unknown_proc_msg((^)/2).
  286unknown_proc_msg((^)/2) -->
  287    !,
  288    [nl, '  ^/2 can only appear as the 2nd argument of setof/3 and bagof/3'].
  289unknown_proc_msg((:-)/2) -->
  290    !,
  291    [nl, '  Rules must be loaded from a file'],
  292    faq('ToplevelMode').
  293unknown_proc_msg((=>)/2) -->
  294    !,
  295    [nl, '  Rules must be loaded from a file'],
  296    faq('ToplevelMode').
  297unknown_proc_msg((:-)/1) -->
  298    !,
  299    [nl, '  Directives must be loaded from a file'],
  300    faq('ToplevelMode').
  301unknown_proc_msg((?-)/1) -->
  302    !,
  303    [nl, '  ?- is the Prolog prompt'],
  304    faq('ToplevelMode').
  305unknown_proc_msg(Proc) -->
  306    { dwim_predicates(Proc, Dwims) },
  307    (   {Dwims \== []}
  308    ->  [nl, '  However, there are definitions for:', nl],
  309        dwim_message(Dwims)
  310    ;   []
  311    ).
  312
  313dependency_error(shared(Shared), private(Private)) -->
  314    [ 'Shared table for ~p may not depend on private ~p'-[Shared, Private] ].
  315dependency_error(Dep, monotonic(On)) -->
  316    { '$pi_head'(PI, Dep),
  317      '$pi_head'(MPI, On)
  318    },
  319    [ 'Dependent ~p on monotonic predicate ~p is not monotonic or incremental'-
  320      [PI, MPI]
  321    ].
  322
  323faq(Page) -->
  324    [nl, '  See FAQ at https://www.swi-prolog.org/FAQ/', Page, '.html' ].
  325
  326type_error_comment(_Expected, Actual) -->
  327    { type_of(Actual, Type),
  328      (   sub_atom(Type, 0, 1, _, First),
  329          memberchk(First, [a,e,i,o,u])
  330      ->  Article = an
  331      ;   Article = a
  332      )
  333    },
  334    [ ' (~w ~w)'-[Article, Type] ].
  335
  336type_of(Term, Type) :-
  337    (   attvar(Term)      -> Type = attvar
  338    ;   var(Term)         -> Type = var
  339    ;   atom(Term)        -> Type = atom
  340    ;   integer(Term)     -> Type = integer
  341    ;   string(Term)      -> Type = string
  342    ;   Term == []        -> Type = empty_list
  343    ;   blob(Term, BlobT) -> blob_type(BlobT, Type)
  344    ;   rational(Term)    -> Type = rational
  345    ;   float(Term)       -> Type = float
  346    ;   is_stream(Term)   -> Type = stream
  347    ;   is_dict(Term)     -> Type = dict
  348    ;   is_list(Term)     -> Type = list
  349    ;   Term = [_|_]      -> list_like(Term, Type)
  350    ;   cyclic_term(Term) -> Type = cyclic
  351    ;   compound(Term)    -> Type = compound
  352    ;                        Type = unknown
  353    ).
  354
  355list_like(Term, Type) :-
  356    '$skip_list'(_, Term, Tail),
  357    (   var(Tail)
  358    ->  Type = partial_list
  359    ;   Type = invalid_list                      % TBD: Better name?
  360    ).
  361
  362blob_type(BlobT, Type) :-
  363    atom_concat(BlobT, '_reference', Type).
  364
  365syntax_error(end_of_clause) -->
  366    [ 'Unexpected end of clause' ].
  367syntax_error(end_of_clause_expected) -->
  368    [ 'End of clause expected' ].
  369syntax_error(end_of_file) -->
  370    [ 'Unexpected end of file' ].
  371syntax_error(end_of_file_in_block_comment) -->
  372    [ 'End of file in /* ... */ comment' ].
  373syntax_error(end_of_file_in_quoted(Quote)) -->
  374    [ 'End of file in quoted ' ],
  375    quoted_type(Quote).
  376syntax_error(illegal_number) -->
  377    [ 'Illegal number' ].
  378syntax_error(long_atom) -->
  379    [ 'Atom too long (see style_check/1)' ].
  380syntax_error(long_string) -->
  381    [ 'String too long (see style_check/1)' ].
  382syntax_error(operator_clash) -->
  383    [ 'Operator priority clash' ].
  384syntax_error(operator_expected) -->
  385    [ 'Operator expected' ].
  386syntax_error(operator_balance) -->
  387    [ 'Unbalanced operator' ].
  388syntax_error(quoted_punctuation) -->
  389    [ 'Operand expected, unquoted comma or bar found' ].
  390syntax_error(list_rest) -->
  391    [ 'Unexpected comma or bar in rest of list' ].
  392syntax_error(cannot_start_term) -->
  393    [ 'Illegal start of term' ].
  394syntax_error(punct(Punct, End)) -->
  395    [ 'Unexpected `~w\' before `~w\''-[Punct, End] ].
  396syntax_error(undefined_char_escape(C)) -->
  397    [ 'Unknown character escape in quoted atom or string: `\\~w\''-[C] ].
  398syntax_error(void_not_allowed) -->
  399    [ 'Empty argument list "()"' ].
  400syntax_error(Term) -->
  401    { compound(Term),
  402      compound_name_arguments(Term, Syntax, [Text])
  403    }, !,
  404    [ '~w expected, found '-[Syntax], ansi(code, '"~w"', [Text]) ].
  405syntax_error(Message) -->
  406    [ '~w'-[Message] ].
  407
  408quoted_type('\'') --> [atom].
  409quoted_type('\"') --> { current_prolog_flag(double_quotes, Type) }, [Type-[]].
  410quoted_type('\`') --> { current_prolog_flag(back_quotes, Type) }, [Type-[]].
  411
  412domain(range(Low,High)) -->
  413    !,
  414    ['[~q..~q]'-[Low,High] ].
  415domain(Domain) -->
  416    ['`~w\''-[Domain] ].

 tabling_existence_error(+Ball, +Context)//

Called on invalid shift/1 calls. Track those that result from tabling errors.

  423tabling_existence_error(Ball, Context) -->
  424    { table_shift_ball(Ball) },
  425    [ 'Tabling dependency error' ],
  426    swi_extra(Context).
  427
  428table_shift_ball(dependency(_Head)).
  429table_shift_ball(dependency(_Skeleton, _Trie, _Mono)).
  430table_shift_ball(call_info(_Skeleton, _Status)).
  431table_shift_ball(call_info(_GenSkeleton, _Skeleton, _Status)).

 dwim_predicates(+PI, -Dwims)

Find related predicate indicators.

  437dwim_predicates(Module:Name/_Arity, Dwims) :-
  438    !,
  439    findall(Dwim, dwim_predicate(Module:Name, Dwim), Dwims).
  440dwim_predicates(Name/_Arity, Dwims) :-
  441    findall(Dwim, dwim_predicate(user:Name, Dwim), Dwims).
  442
  443dwim_message([]) --> [].
  444dwim_message([M:Head|T]) -->
  445    { hidden_module(M),
  446      !,
  447      functor(Head, Name, Arity)
  448    },
  449    [ '        ~q'-[Name/Arity], nl ],
  450    dwim_message(T).
  451dwim_message([Module:Head|T]) -->
  452    !,
  453    { functor(Head, Name, Arity)
  454    },
  455    [ '        ~q'-[Module:Name/Arity], nl],
  456    dwim_message(T).
  457dwim_message([Head|T]) -->
  458    {functor(Head, Name, Arity)},
  459    [ '        ~q'-[Name/Arity], nl],
  460    dwim_message(T).
  461
  462
  463swi_message(io_error(Op, Stream)) -->
  464    [ 'I/O error in ~w on stream ~p'-[Op, Stream] ].
  465swi_message(thread_error(TID, false)) -->
  466    [ 'Thread ~p died due to failure:'-[TID] ].
  467swi_message(thread_error(TID, exception(Error))) -->
  468    [ 'Thread ~p died abnormally:'-[TID], nl ],
  469    translate_message(Error).
  470swi_message(dependency_error(Tabled, DependsOn)) -->
  471    dependency_error(Tabled, DependsOn).
  472swi_message(shell(execute, Cmd)) -->
  473    [ 'Could not execute `~w'''-[Cmd] ].
  474swi_message(shell(signal(Sig), Cmd)) -->
  475    [ 'Caught signal ~d on `~w'''-[Sig, Cmd] ].
  476swi_message(format(Fmt, Args)) -->
  477    [ Fmt-Args ].
  478swi_message(signal(Name, Num)) -->
  479    [ 'Caught signal ~d (~w)'-[Num, Name] ].
  480swi_message(limit_exceeded(Limit, MaxVal)) -->
  481    [ 'Exceeded ~w limit (~w)'-[Limit, MaxVal] ].
  482swi_message(goal_failed(Goal)) -->
  483    [ 'goal unexpectedly failed: ~p'-[Goal] ].
  484swi_message(shared_object(_Action, Message)) --> % Message = dlerror()
  485    [ '~w'-[Message] ].
  486swi_message(system_error(Error)) -->
  487    [ 'error in system call: ~w'-[Error]
  488    ].
  489swi_message(system_error) -->
  490    [ 'error in system call'
  491    ].
  492swi_message(failure_error(Goal)) -->
  493    [ 'Goal failed: ~p'-[Goal] ].
  494swi_message(timeout_error(Op, Stream)) -->
  495    [ 'Timeout in ~w from ~p'-[Op, Stream] ].
  496swi_message(not_implemented(Type, What)) -->
  497    [ '~w `~p\' is not implemented in this version'-[Type, What] ].
  498swi_message(context_error(nodirective, Goal)) -->
  499    { goal_to_predicate_indicator(Goal, PI) },
  500    [ 'Wrong context: ~p can only be used in a directive'-[PI] ].
  501swi_message(context_error(edit, no_default_file)) -->
  502    (   { current_prolog_flag(windows, true) }
  503    ->  [ 'Edit/0 can only be used after opening a \c
  504               Prolog file by double-clicking it' ]
  505    ;   [ 'Edit/0 can only be used with the "-s file" commandline option'
  506        ]
  507    ),
  508    [ nl, 'Use "?- edit(Topic)." or "?- emacs."' ].
  509swi_message(context_error(function, meta_arg(S))) -->
  510    [ 'Functions are not (yet) supported for meta-arguments of type ~q'-[S] ].
  511swi_message(format_argument_type(Fmt, Arg)) -->
  512    [ 'Illegal argument to format sequence ~~~w: ~p'-[Fmt, Arg] ].
  513swi_message(format(Msg)) -->
  514    [ 'Format error: ~w'-[Msg] ].
  515swi_message(conditional_compilation_error(unterminated, File:Line)) -->
  516    [ 'Unterminated conditional compilation from '-[], url(File:Line) ].
  517swi_message(conditional_compilation_error(no_if, What)) -->
  518    [ ':- ~w without :- if'-[What] ].
  519swi_message(duplicate_key(Key)) -->
  520    [ 'Duplicate key: ~p'-[Key] ].
  521swi_message(initialization_error(failed, Goal, File:Line)) -->
  522    !,
  523    [ url(File:Line), ': ~p: false'-[Goal] ].
  524swi_message(initialization_error(Error, Goal, File:Line)) -->
  525    [ url(File:Line), ': ~p '-[Goal] ],
  526    translate_message(Error).
  527swi_message(determinism_error(PI, det, Found, property)) -->
  528    (   { '$pi_head'(user:PI, Head),
  529          predicate_property(Head, det)
  530        }
  531    ->  [ 'Deterministic procedure ~p'-[PI] ]
  532    ;   [ 'Procedure ~p called from a deterministic procedure'-[PI] ]
  533    ),
  534    det_error(Found).
  535swi_message(determinism_error(PI, det, fail, guard)) -->
  536    [ 'Procedure ~p failed after $-guard'-[PI] ].
  537swi_message(determinism_error(PI, det, fail, guard_in_caller)) -->
  538    [ 'Procedure ~p failed after $-guard in caller'-[PI] ].
  539swi_message(determinism_error(Goal, det, fail, goal)) -->
  540    [ 'Goal ~p failed'-[Goal] ].
  541swi_message(determinism_error(Goal, det, nondet, goal)) -->
  542    [ 'Goal ~p succeeded with a choice point'-[Goal] ].
  543swi_message(qlf_format_error(File, Message)) -->
  544    [ '~w: Invalid QLF file: ~w'-[File, Message] ].
  545swi_message(goal_expansion_error(bound, Term)) -->
  546    [ 'Goal expansion bound a variable to ~p'-[Term] ].
  547
  548det_error(nondet) -->
  549    [ ' succeeded with a choicepoint'- [] ].
  550det_error(fail) -->
  551    [ ' failed'- [] ].

 swi_location(+Term)// is det

Print location information for error(Formal, ImplDefined) from the ImplDefined term.

  559:- public swi_location//1.  560swi_location(X) -->
  561    { var(X) },
  562    !.
  563swi_location(Context) -->
  564    { message_lang(Lang) },
  565    prolog:message_location(Lang, Context),
  566    !.
  567swi_location(Context) -->
  568    prolog:message_location(Context),
  569    !.
  570swi_location(context(Caller, _Msg)) -->
  571    { ground(Caller) },
  572    !,
  573    caller(Caller).
  574swi_location(file(Path, Line, -1, _CharNo)) -->
  575    !,
  576    [ url(Path:Line), ': ' ].
  577swi_location(file(Path, Line, LinePos, _CharNo)) -->
  578    [ url(Path:Line:LinePos), ': ' ].
  579swi_location(stream(Stream, Line, LinePos, CharNo)) -->
  580    (   { is_stream(Stream),
  581          stream_property(Stream, file_name(File))
  582        }
  583    ->  swi_location(file(File, Line, LinePos, CharNo))
  584    ;   [ 'Stream ~w:~d:~d '-[Stream, Line, LinePos] ]
  585    ).
  586swi_location(autoload(File:Line)) -->
  587    [ url(File:Line), ': ' ].
  588swi_location(_) -->
  589    [].
  590
  591caller(system:'$record_clause'/3) -->
  592    !,
  593    [].
  594caller(Module:Name/Arity) -->
  595    !,
  596    (   { \+ hidden_module(Module) }
  597    ->  [ '~q:~q/~w: '-[Module, Name, Arity] ]
  598    ;   [ '~q/~w: '-[Name, Arity] ]
  599    ).
  600caller(Name/Arity) -->
  601    [ '~q/~w: '-[Name, Arity] ].
  602caller(Caller) -->
  603    [ '~p: '-[Caller] ].

 swi_extra(+Term)// is det

Extract information from the second argument of an error(Formal, ImplDefined) that is printed after the core of the message.

See also

- swi_location//1 uses the same term to insert context before the core of the message.

  614swi_extra(X) -->
  615    { var(X) },
  616    !,
  617    [].
  618swi_extra(Context) -->
  619    { message_lang(Lang) },
  620    prolog:message_context(Lang, Context),
  621    !.
  622swi_extra(Context) -->
  623    prolog:message_context(Context).
  624swi_extra(context(_, Msg)) -->
  625    { nonvar(Msg),
  626      Msg \== ''
  627    },
  628    !,
  629    swi_comment(Msg).
  630swi_extra(string(String, CharPos)) -->
  631    { sub_string(String, 0, CharPos, _, Before),
  632      sub_string(String, CharPos, _, 0, After)
  633    },
  634    [ nl, '~w'-[Before], nl, '** here **', nl, '~w'-[After] ].
  635swi_extra(_) -->
  636    [].
  637
  638swi_comment(already_from(Module)) -->
  639    !,
  640    [ ' (already imported from ~q)'-[Module] ].
  641swi_comment(directory(_Dir)) -->
  642    !,
  643    [ ' (is a directory)' ].
  644swi_comment(not_a_directory(_Dir)) -->
  645    !,
  646    [ ' (is not a directory)' ].
  647swi_comment(Msg) -->
  648    [ ' (~w)'-[Msg] ].
  649
  650
  651thread_context -->
  652    { \+ current_prolog_flag(toplevel_thread, true),
  653      thread_self(Id)
  654    },
  655    !,
  656    ['[Thread ~w] '-[Id]].
  657thread_context -->
  658    [].
  659
  660		 /*******************************
  661		 *        UNWIND MESSAGES	*
  662		 *******************************/
  663
  664unwind_message(Var) -->
  665    { var(Var) }, !,
  666    [ 'Unknown unwind message: ~p'-[Var] ].
  667unwind_message(abort) -->
  668    [ 'Execution Aborted' ].
  669unwind_message(halt(_)) -->
  670    [].
  671unwind_message(thread_exit(Term)) -->
  672    [ 'Invalid thread_exit/1.  Payload: ~p'-[Term] ].
  673unwind_message(Term) -->
  674    [ 'Unknown "unwind" exception: ~p'-[Term] ].
  675
  676
  677                 /*******************************
  678                 *        NORMAL MESSAGES       *
  679                 *******************************/
  680
  681:- dynamic prolog:version_msg/1.  682:- multifile prolog:version_msg/1.  683
  684prolog_message(welcome) -->
  685    [ 'Welcome to SWI-Prolog (' ],
  686    prolog_message(threads),
  687    prolog_message(address_bits),
  688    ['version ' ],
  689    prolog_message(version),
  690    [ ')', nl ],
  691    prolog_message(copyright),
  692    [ nl ],
  693    translate_message(user_versions),
  694    [ nl ],
  695    prolog_message(documentaton),
  696    [ nl, nl ].
  697prolog_message(user_versions) -->
  698    (   { findall(Msg, prolog:version_msg(Msg), Msgs),
  699          Msgs \== []
  700        }
  701    ->  [nl],
  702        user_version_messages(Msgs)
  703    ;   []
  704    ).
  705prolog_message(deprecated(Term)) -->
  706    { nonvar(Term) },
  707    (   { message_lang(Lang) },
  708        prolog:deprecated(Lang, Term)
  709    ->  []
  710    ;   prolog:deprecated(Term)
  711    ->  []
  712    ;   deprecated(Term)
  713    ).
  714prolog_message(unhandled_exception(E)) -->
  715    { nonvar(E) },
  716    [ 'Unhandled exception: ' ],
  717    (   translate_message(E)
  718    ->  []
  719    ;   [ '~p'-[E] ]
  720    ).

 prolog_message(+Term)//

  724prolog_message(initialization_error(_, E, File:Line)) -->
  725    !,
  726    [ url(File:Line),
  727      ': Initialization goal raised exception:', nl
  728    ],
  729    translate_message(E).
  730prolog_message(initialization_error(Goal, E, _)) -->
  731    [ 'Initialization goal ~p raised exception:'-[Goal], nl ],
  732    translate_message(E).
  733prolog_message(initialization_failure(_Goal, File:Line)) -->
  734    !,
  735    [ url(File:Line),
  736      ': Initialization goal failed'-[]
  737    ].
  738prolog_message(initialization_failure(Goal, _)) -->
  739    [ 'Initialization goal failed: ~p'-[Goal]
  740    ].
  741prolog_message(initialization_exception(E)) -->
  742    [ 'Prolog initialisation failed:', nl ],
  743    translate_message(E).
  744prolog_message(init_goal_syntax(Error, Text)) -->
  745    !,
  746    [ '-g ~w: '-[Text] ],
  747    translate_message(Error).
  748prolog_message(init_goal_failed(failed, @(Goal,File:Line))) -->
  749    !,
  750    [ url(File:Line), ': ~p: false'-[Goal] ].
  751prolog_message(init_goal_failed(Error, @(Goal,File:Line))) -->
  752    !,
  753    [ url(File:Line), ': ~p '-[Goal] ],
  754    translate_message(Error).
  755prolog_message(init_goal_failed(failed, Text)) -->
  756    !,
  757    [ '-g ~w: false'-[Text] ].
  758prolog_message(init_goal_failed(Error, Text)) -->
  759    !,
  760    [ '-g ~w: '-[Text] ],
  761    translate_message(Error).
  762prolog_message(goal_failed(Context, Goal)) -->
  763    [ 'Goal (~w) failed: ~p'-[Context, Goal] ].
  764prolog_message(no_current_module(Module)) -->
  765    [ '~w is not a current module (created)'-[Module] ].
  766prolog_message(commandline_arg_type(Flag, Arg)) -->
  767    [ 'Bad argument to commandline option -~w: ~w'-[Flag, Arg] ].
  768prolog_message(missing_feature(Name)) -->
  769    [ 'This version of SWI-Prolog does not support ~w'-[Name] ].
  770prolog_message(singletons(_Term, List)) -->
  771    [ 'Singleton variables: ~w'-[List] ].
  772prolog_message(multitons(_Term, List)) -->
  773    [ 'Singleton-marked variables appearing more than once: ~w'-[List] ].
  774prolog_message(profile_no_cpu_time) -->
  775    [ 'No CPU-time info.  Check the SWI-Prolog manual for details' ].
  776prolog_message(non_ascii(Text, Type)) -->
  777    [ 'Unquoted ~w with non-portable characters: ~w'-[Type, Text] ].
  778prolog_message(io_warning(Stream, Message)) -->
  779    { stream_property(Stream, position(Position)),
  780      !,
  781      stream_position_data(line_count, Position, LineNo),
  782      stream_position_data(line_position, Position, LinePos),
  783      (   stream_property(Stream, file_name(File))
  784      ->  Obj = File
  785      ;   Obj = Stream
  786      )
  787    },
  788    [ '~p:~d:~d: ~w'-[Obj, LineNo, LinePos, Message] ].
  789prolog_message(io_warning(Stream, Message)) -->
  790    [ 'stream ~p: ~w'-[Stream, Message] ].
  791prolog_message(option_usage(pldoc)) -->
  792    [ 'Usage: --pldoc[=port]' ].
  793prolog_message(interrupt(begin)) -->
  794    [ 'Action (h for help) ? ', flush ].
  795prolog_message(interrupt(end)) -->
  796    [ 'continue' ].
  797prolog_message(interrupt(trace)) -->
  798    [ 'continue (trace mode)' ].
  799prolog_message(unknown_in_module_user) -->
  800    [ 'Using a non-error value for unknown in the global module', nl,
  801      'causes most of the development environment to stop working.', nl,
  802      'Please use :- dynamic or limit usage of unknown to a module.', nl,
  803      'See https://www.swi-prolog.org/howto/database.html'
  804    ].
  805prolog_message(untable(PI)) -->
  806    [ 'Reconsult: removed tabling for ~p'-[PI] ].
  807prolog_message(unknown_option(Set, Opt)) -->
  808    [ 'Unknown ~w option: ~p'-[Set, Opt] ].
  809
  810
  811                 /*******************************
  812                 *         LOADING FILES        *
  813                 *******************************/
  814
  815prolog_message(modify_active_procedure(Who, What)) -->
  816    [ '~p: modified active procedure ~p'-[Who, What] ].
  817prolog_message(load_file(failed(user:File))) -->
  818    [ 'Failed to load ~p'-[File] ].
  819prolog_message(load_file(failed(Module:File))) -->
  820    [ 'Failed to load ~p into module ~p'-[File, Module] ].
  821prolog_message(load_file(failed(File))) -->
  822    [ 'Failed to load ~p'-[File] ].
  823prolog_message(mixed_directive(Goal)) -->
  824    [ 'Cannot pre-compile mixed load/call directive: ~p'-[Goal] ].
  825prolog_message(cannot_redefine_comma) -->
  826    [ 'Full stop in clause-body?  Cannot redefine ,/2' ].
  827prolog_message(illegal_autoload_index(Dir, Term)) -->
  828    [ 'Illegal term in INDEX file of directory ~w: ~w'-[Dir, Term] ].
  829prolog_message(redefined_procedure(Type, Proc)) -->
  830    [ 'Redefined ~w procedure ~p'-[Type, Proc] ],
  831    defined_definition('Previously defined', Proc).
  832prolog_message(declare_module(Module, abolish(Predicates))) -->
  833    [ 'Loading module ~w abolished: ~p'-[Module, Predicates] ].
  834prolog_message(import_private(Module, Private)) -->
  835    [ 'import/1: ~p is not exported (still imported into ~q)'-
  836      [Private, Module]
  837    ].
  838prolog_message(ignored_weak_import(Into, From:PI)) -->
  839    [ 'Local definition of ~p overrides weak import from ~q'-
  840      [Into:PI, From]
  841    ].
  842prolog_message(undefined_export(Module, PI)) -->
  843    [ 'Exported procedure ~q:~q is not defined'-[Module, PI] ].
  844prolog_message(no_exported_op(Module, Op)) -->
  845    [ 'Operator ~q:~q is not exported (still defined)'-[Module, Op] ].
  846prolog_message(discontiguous((-)/2,_)) -->
  847    prolog_message(minus_in_identifier).
  848prolog_message(discontiguous(Proc,Current)) -->
  849    [ 'Clauses of ', ansi(code, '~p', [Proc]),
  850      ' are not together in the source-file', nl ],
  851    current_definition(Proc, 'Earlier definition at '),
  852    [ 'Current predicate: ', ansi(code, '~p', [Current]), nl,
  853      'Use ', ansi(code, ':- discontiguous ~p.', [Proc]),
  854      ' to suppress this message'
  855    ].
  856prolog_message(decl_no_effect(Goal)) -->
  857    [ 'Deprecated declaration has no effect: ~p'-[Goal] ].
  858prolog_message(load_file(start(Level, File))) -->
  859    [ '~|~t~*+Loading '-[Level] ],
  860    load_file(File),
  861    [ ' ...' ].
  862prolog_message(include_file(start(Level, File))) -->
  863    [ '~|~t~*+include '-[Level] ],
  864    load_file(File),
  865    [ ' ...' ].
  866prolog_message(include_file(done(Level, File))) -->
  867    [ '~|~t~*+included '-[Level] ],
  868    load_file(File).
  869prolog_message(load_file(done(Level, File, Action, Module, Time, Clauses))) -->
  870    [ '~|~t~*+'-[Level] ],
  871    load_file(File),
  872    [ ' ~w'-[Action] ],
  873    load_module(Module),
  874    [ ' ~2f sec, ~D clauses'-[Time, Clauses] ].
  875prolog_message(dwim_undefined(Goal, Alternatives)) -->
  876    { goal_to_predicate_indicator(Goal, Pred)
  877    },
  878    [ 'Unknown procedure: ~q'-[Pred], nl,
  879      '    However, there are definitions for:', nl
  880    ],
  881    dwim_message(Alternatives).
  882prolog_message(dwim_correct(Into)) -->
  883    [ 'Correct to: ~q? '-[Into], flush ].
  884prolog_message(error(loop_error(Spec), file_search(Used))) -->
  885    [ 'File search: too many levels of indirections on: ~p'-[Spec], nl,
  886      '    Used alias expansions:', nl
  887    ],
  888    used_search(Used).
  889prolog_message(minus_in_identifier) -->
  890    [ 'The "-" character should not be used to separate words in an', nl,
  891      'identifier.  Check the SWI-Prolog FAQ for details.'
  892    ].
  893prolog_message(qlf(removed_after_error(File))) -->
  894    [ 'Removed incomplete QLF file ~w'-[File] ].
  895prolog_message(qlf(recompile(Spec,_Pl,_Qlf,Reason))) -->
  896    [ '~p: recompiling QLF file'-[Spec] ],
  897    qlf_recompile_reason(Reason).
  898prolog_message(qlf(can_not_recompile(Spec,QlfFile,_Reason))) -->
  899    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  900      '\tLoading from source'-[]
  901    ].
  902prolog_message(qlf(system_lib_out_of_date(Spec,QlfFile))) -->
  903    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  904      '\tLoading QlfFile'-[]
  905    ].
  906prolog_message(redefine_module(Module, OldFile, File)) -->
  907    [ 'Module "~q" already loaded from ~w.'-[Module, OldFile], nl,
  908      'Wipe and reload from ~w? '-[File], flush
  909    ].
  910prolog_message(redefine_module_reply) -->
  911    [ 'Please answer y(es), n(o) or a(bort)' ].
  912prolog_message(reloaded_in_module(Absolute, OldContext, LM)) -->
  913    [ '~w was previously loaded in module ~w'-[Absolute, OldContext], nl,
  914      '\tnow it is reloaded into module ~w'-[LM] ].
  915prolog_message(expected_layout(Expected, Pos)) -->
  916    [ 'Layout data: expected ~w, found: ~p'-[Expected, Pos] ].
  917
  918defined_definition(Message, Spec) -->
  919    { strip_module(user:Spec, M, Name/Arity),
  920      functor(Head, Name, Arity),
  921      predicate_property(M:Head, file(File)),
  922      predicate_property(M:Head, line_count(Line))
  923    },
  924    !,
  925    [ nl, '~w at '-[Message], url(File:Line) ].
  926defined_definition(_, _) --> [].
  927
  928used_search([]) -->
  929    [].
  930used_search([Alias=Expanded|T]) -->
  931    [ '        file_search_path(~p, ~p)'-[Alias, Expanded], nl ],
  932    used_search(T).
  933
  934load_file(file(Spec, _Path)) -->
  935    (   {atomic(Spec)}
  936    ->  [ '~w'-[Spec] ]
  937    ;   [ '~p'-[Spec] ]
  938    ).
  939%load_file(file(_, Path)) -->
  940%       [ '~w'-[Path] ].
  941
  942load_module(user) --> !.
  943load_module(system) --> !.
  944load_module(Module) -->
  945    [ ' into ~w'-[Module] ].
  946
  947goal_to_predicate_indicator(Goal, PI) :-
  948    strip_module(Goal, Module, Head),
  949    callable_name_arity(Head, Name, Arity),
  950    user_predicate_indicator(Module:Name/Arity, PI).
  951
  952callable_name_arity(Goal, Name, Arity) :-
  953    compound(Goal),
  954    !,
  955    compound_name_arity(Goal, Name, Arity).
  956callable_name_arity(Goal, Goal, 0) :-
  957    atom(Goal).
  958
  959user_predicate_indicator(Module:PI, PI) :-
  960    hidden_module(Module),
  961    !.
  962user_predicate_indicator(PI, PI).
  963
  964hidden_module(user) :- !.
  965hidden_module(system) :- !.
  966hidden_module(M) :-
  967    sub_atom(M, 0, _, _, $).
  968
  969current_definition(Proc, Prefix) -->
  970    { pi_uhead(Proc, Head),
  971      predicate_property(Head, file(File)),
  972      predicate_property(Head, line_count(Line))
  973    },
  974    [ '~w'-[Prefix], url(File:Line), nl ].
  975current_definition(_, _) --> [].
  976
  977pi_uhead(Module:Name/Arity, Module:Head) :-
  978    !,
  979    atom(Module), atom(Name), integer(Arity),
  980    functor(Head, Name, Arity).
  981pi_uhead(Name/Arity, user:Head) :-
  982    atom(Name), integer(Arity),
  983    functor(Head, Name, Arity).
  984
  985qlf_recompile_reason(old) -->
  986    !,
  987    [ ' (out of date)'-[] ].
  988qlf_recompile_reason(_) -->
  989    [ ' (incompatible with current Prolog version)'-[] ].
  990
  991prolog_message(file_search(cache(Spec, _Cond), Path)) -->
  992    [ 'File search: ~p --> ~p (cache)'-[Spec, Path] ].
  993prolog_message(file_search(found(Spec, Cond), Path)) -->
  994    [ 'File search: ~p --> ~p OK ~p'-[Spec, Path, Cond] ].
  995prolog_message(file_search(tried(Spec, Cond), Path)) -->
  996    [ 'File search: ~p --> ~p NO ~p'-[Spec, Path, Cond] ].
  997
  998                 /*******************************
  999                 *              GC              *
 1000                 *******************************/
 1001
 1002prolog_message(agc(start)) -->
 1003    thread_context,
 1004    [ 'AGC: ', flush ].
 1005prolog_message(agc(done(Collected, Remaining, Time))) -->
 1006    [ at_same_line,
 1007      'reclaimed ~D atoms in ~3f sec. (remaining: ~D)'-
 1008      [Collected, Time, Remaining]
 1009    ].
 1010prolog_message(cgc(start)) -->
 1011    thread_context,
 1012    [ 'CGC: ', flush ].
 1013prolog_message(cgc(done(CollectedClauses, _CollectedBytes,
 1014                        RemainingBytes, Time))) -->
 1015    [ at_same_line,
 1016      'reclaimed ~D clauses in ~3f sec. (pending: ~D bytes)'-
 1017      [CollectedClauses, Time, RemainingBytes]
 1018    ].
 1019
 1020		 /*******************************
 1021		 *        STACK OVERFLOW	*
 1022		 *******************************/
 1023
 1024out_of_stack(Context) -->
 1025    { human_stack_size(Context.localused,   Local),
 1026      human_stack_size(Context.globalused,  Global),
 1027      human_stack_size(Context.trailused,   Trail),
 1028      human_stack_size(Context.stack_limit, Limit),
 1029      LCO is (100*(Context.depth - Context.environments))/Context.depth
 1030    },
 1031    [ 'Stack limit (~s) exceeded'-[Limit], nl,
 1032      '  Stack sizes: local: ~s, global: ~s, trail: ~s'-[Local,Global,Trail], nl,
 1033      '  Stack depth: ~D, last-call: ~0f%, Choice points: ~D'-
 1034         [Context.depth, LCO, Context.choicepoints], nl
 1035    ],
 1036    overflow_reason(Context, Resolve),
 1037    resolve_overflow(Resolve).
 1038
 1039human_stack_size(Size, String) :-
 1040    Size < 100,
 1041    format(string(String), '~dKb', [Size]).
 1042human_stack_size(Size, String) :-
 1043    Size < 100 000,
 1044    Value is Size / 1024,
 1045    format(string(String), '~1fMb', [Value]).
 1046human_stack_size(Size, String) :-
 1047    Value is Size / (1024*1024),
 1048    format(string(String), '~1fGb', [Value]).
 1049
 1050overflow_reason(Context, fix) -->
 1051    show_non_termination(Context),
 1052    !.
 1053overflow_reason(Context, enlarge) -->
 1054    { Stack = Context.get(stack) },
 1055    !,
 1056    [ '  In:'-[], nl ],
 1057    stack(Stack).
 1058overflow_reason(_Context, enlarge) -->
 1059    [ '  Insufficient global stack'-[] ].
 1060
 1061show_non_termination(Context) -->
 1062    (   { Stack = Context.get(cycle) }
 1063    ->  [ '  Probable infinite recursion (cycle):'-[], nl ]
 1064    ;   { Stack = Context.get(non_terminating) }
 1065    ->  [ '  Possible non-terminating recursion:'-[], nl ]
 1066    ),
 1067    stack(Stack).
 1068
 1069stack([]) --> [].
 1070stack([frame(Depth, M:Goal, _)|T]) -->
 1071    [ '    [~D] ~q:'-[Depth, M] ],
 1072    stack_goal(Goal),
 1073    [ nl ],
 1074    stack(T).
 1075
 1076stack_goal(Goal) -->
 1077    { compound(Goal),
 1078      !,
 1079      compound_name_arity(Goal, Name, Arity)
 1080    },
 1081    [ '~q('-[Name] ],
 1082    stack_goal_args(1, Arity, Goal),
 1083    [ ')'-[] ].
 1084stack_goal(Goal) -->
 1085    [ '~q'-[Goal] ].
 1086
 1087stack_goal_args(I, Arity, Goal) -->
 1088    { I =< Arity,
 1089      !,
 1090      arg(I, Goal, A),
 1091      I2 is I + 1
 1092    },
 1093    stack_goal_arg(A),
 1094    (   { I2 =< Arity }
 1095    ->  [ ', '-[] ],
 1096        stack_goal_args(I2, Arity, Goal)
 1097    ;   []
 1098    ).
 1099stack_goal_args(_, _, _) -->
 1100    [].
 1101
 1102stack_goal_arg(A) -->
 1103    { nonvar(A),
 1104      A = [Len|T],
 1105      !
 1106    },
 1107    (   {Len == cyclic_term}
 1108    ->  [ '[cyclic list]'-[] ]
 1109    ;   {T == []}
 1110    ->  [ '[length:~D]'-[Len] ]
 1111    ;   [ '[length:~D|~p]'-[Len, T] ]
 1112    ).
 1113stack_goal_arg(A) -->
 1114    { nonvar(A),
 1115      A = _/_,
 1116      !
 1117    },
 1118    [ '<compound ~p>'-[A] ].
 1119stack_goal_arg(A) -->
 1120    [ '~p'-[A] ].
 1121
 1122resolve_overflow(fix) -->
 1123    [].
 1124resolve_overflow(enlarge) -->
 1125    { current_prolog_flag(stack_limit, LimitBytes),
 1126      NewLimit is LimitBytes * 2
 1127    },
 1128    [ nl,
 1129      'Use the --stack_limit=size[KMG] command line option or'-[], nl,
 1130      '?- set_prolog_flag(stack_limit, ~I). to double the limit.'-[NewLimit]
 1131    ].

 out_of_c_stack

The thread's C-stack limit was exceeded. Give some advice on how to resolve this.

 1138out_of_c_stack -->
 1139    { statistics(c_stack, Limit), Limit > 0 },
 1140    !,
 1141    [ 'C-stack limit (~D bytes) exceeded.'-[Limit], nl ],
 1142    resolve_c_stack_overflow(Limit).
 1143out_of_c_stack -->
 1144    { statistics(c_stack, Limit), Limit > 0 },
 1145    [ 'C-stack limit exceeded.'-[Limit], nl ],
 1146    resolve_c_stack_overflow(Limit).
 1147
 1148resolve_c_stack_overflow(_Limit) -->
 1149    { thread_self(main) },
 1150    [ 'Use the shell command ' ], code('~w', 'ulimit -s size'),
 1151    [ ' to enlarge the limit.' ].
 1152resolve_c_stack_overflow(_Limit) -->
 1153    [ 'Use the ' ], code('~w', 'c_stack(KBytes)'),
 1154    [ ' option of '], code(thread_create/3), [' to enlarge the limit.' ].
 1155
 1156
 1157                 /*******************************
 1158                 *        MAKE/AUTOLOAD         *
 1159                 *******************************/
 1160
 1161prolog_message(make(reload(Files))) -->
 1162    { length(Files, N)
 1163    },
 1164    [ 'Make: reloading ~D files'-[N] ].
 1165prolog_message(make(done(_Files))) -->
 1166    [ 'Make: finished' ].
 1167prolog_message(make(library_index(Dir))) -->
 1168    [ 'Updating index for library ~w'-[Dir] ].
 1169prolog_message(autoload(Pred, File)) -->
 1170    thread_context,
 1171    [ 'autoloading ~p from ~w'-[Pred, File] ].
 1172prolog_message(autoload(read_index(Dir))) -->
 1173    [ 'Loading autoload index for ~w'-[Dir] ].
 1174prolog_message(autoload(disabled(Loaded))) -->
 1175    [ 'Disabled autoloading (loaded ~D files)'-[Loaded] ].
 1176prolog_message(autoload(already_defined(PI, From))) -->
 1177    code(PI),
 1178    (   { '$pi_head'(PI, Head),
 1179          predicate_property(Head, built_in)
 1180        }
 1181    ->  [' is a built-in predicate']
 1182    ;   [ ' is already imported from module ' ],
 1183        code(From)
 1184    ).
 1185
 1186swi_message(autoload(Msg)) -->
 1187    [ nl, '  ' ],
 1188    autoload_message(Msg).
 1189
 1190autoload_message(not_exported(PI, Spec, _FullFile, _Exports)) -->
 1191    [ ansi(code, '~w', [Spec]),
 1192      ' does not export ',
 1193      ansi(code, '~p', [PI])
 1194    ].
 1195autoload_message(no_file(Spec)) -->
 1196    [ ansi(code, '~p', [Spec]), ': No such file' ].
 1197
 1198
 1199                 /*******************************
 1200                 *       COMPILER WARNINGS      *
 1201                 *******************************/
 1202
 1203% print warnings about dubious code raised by the compiler.
 1204% TBD: pass in PC to produce exact error locations.
 1205
 1206prolog_message(compiler_warnings(Clause, Warnings0)) -->
 1207    {   print_goal_options(DefOptions),
 1208        (   prolog_load_context(variable_names, VarNames)
 1209        ->  warnings_with_named_vars(Warnings0, VarNames, Warnings),
 1210            Options = [variable_names(VarNames)|DefOptions]
 1211        ;   Options = DefOptions,
 1212            Warnings = Warnings0
 1213        )
 1214    },
 1215    compiler_warnings(Warnings, Clause, Options).
 1216
 1217warnings_with_named_vars([], _, []).
 1218warnings_with_named_vars([H|T0], VarNames, [H|T]) :-
 1219    term_variables(H, Vars),
 1220    '$member'(V1, Vars),
 1221    '$member'(_=V2, VarNames),
 1222    V1 == V2,
 1223    !,
 1224    warnings_with_named_vars(T0, VarNames, T).
 1225warnings_with_named_vars([_|T0], VarNames, T) :-
 1226    warnings_with_named_vars(T0, VarNames, T).
 1227
 1228
 1229compiler_warnings([], _, _) --> [].
 1230compiler_warnings([H|T], Clause, Options) -->
 1231    (   compiler_warning(H, Clause, Options)
 1232    ->  []
 1233    ;   [ 'Unknown compiler warning: ~W'-[H,Options] ]
 1234    ),
 1235    (   {T==[]}
 1236    ->  []
 1237    ;   [nl]
 1238    ),
 1239    compiler_warnings(T, Clause, Options).
 1240
 1241compiler_warning(eq_vv(A,B), _Clause, Options) -->
 1242    (   { A == B }
 1243    ->  [ 'Test is always true: ~W'-[A==B, Options] ]
 1244    ;   [ 'Test is always false: ~W'-[A==B, Options] ]
 1245    ).
 1246compiler_warning(eq_singleton(A,B), _Clause, Options) -->
 1247    [ 'Test is always false: ~W'-[A==B, Options] ].
 1248compiler_warning(neq_vv(A,B), _Clause, Options) -->
 1249    (   { A \== B }
 1250    ->  [ 'Test is always true: ~W'-[A\==B, Options] ]
 1251    ;   [ 'Test is always false: ~W'-[A\==B, Options] ]
 1252    ).
 1253compiler_warning(neq_singleton(A,B), _Clause, Options) -->
 1254    [ 'Test is always true: ~W'-[A\==B, Options] ].
 1255compiler_warning(unify_singleton(A,B), _Clause, Options) -->
 1256    [ 'Unified variable is not used: ~W'-[A=B, Options] ].
 1257compiler_warning(always(Bool, Pred, Arg), _Clause, Options) -->
 1258    { Goal =.. [Pred,Arg] },
 1259    [ 'Test is always ~w: ~W'-[Bool, Goal, Options] ].
 1260compiler_warning(unbalanced_var(V), _Clause, Options) -->
 1261    [ 'Variable not introduced in all branches: ~W'-[V, Options] ].
 1262compiler_warning(branch_singleton(V), _Clause, Options) -->
 1263    [ 'Singleton variable in branch: ~W'-[V, Options] ].
 1264compiler_warning(negation_singleton(V), _Clause, Options) -->
 1265    [ 'Singleton variable in \\+: ~W'-[V, Options] ].
 1266compiler_warning(multiton(V), _Clause, Options) -->
 1267    [ 'Singleton-marked variable appears more than once: ~W'-[V, Options] ].
 1268
 1269print_goal_options(
 1270    [ quoted(true),
 1271      portray(true)
 1272    ]).
 1273
 1274
 1275                 /*******************************
 1276                 *      TOPLEVEL MESSAGES       *
 1277                 *******************************/
 1278
 1279prolog_message(version) -->
 1280    { current_prolog_flag(version_git, Version) },
 1281    !,
 1282    [ '~w'-[Version] ].
 1283prolog_message(version) -->
 1284    { current_prolog_flag(version_data, swi(Major,Minor,Patch,Options))
 1285    },
 1286    (   { memberchk(tag(Tag), Options) }
 1287    ->  [ '~w.~w.~w-~w'-[Major, Minor, Patch, Tag] ]
 1288    ;   [ '~w.~w.~w'-[Major, Minor, Patch] ]
 1289    ).
 1290prolog_message(address_bits) -->
 1291    { current_prolog_flag(address_bits, Bits)
 1292    },
 1293    !,
 1294    [ '~d bits, '-[Bits] ].
 1295prolog_message(threads) -->
 1296    { current_prolog_flag(threads, true)
 1297    },
 1298    !,
 1299    [ 'threaded, ' ].
 1300prolog_message(threads) -->
 1301    [].
 1302prolog_message(copyright) -->
 1303    [ 'SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.', nl,
 1304      'Please run ', ansi(code, '?- license.', []), ' for legal details.'
 1305    ].
 1306prolog_message(documentaton) -->
 1307    [ 'For online help and background, visit ', url('https://www.swi-prolog.org') ],
 1308    (   { exists_source(library(help)) }
 1309    ->  [ nl,
 1310          'For built-in help, use ', ansi(code, '?- help(Topic).', []),
 1311          ' or ', ansi(code, '?- apropos(Word).', [])
 1312        ]
 1313    ;   []
 1314    ).
 1315prolog_message(about) -->
 1316    [ 'SWI-Prolog version (' ],
 1317    prolog_message(threads),
 1318    prolog_message(address_bits),
 1319    ['version ' ],
 1320    prolog_message(version),
 1321    [ ')', nl ],
 1322    prolog_message(copyright).
 1323prolog_message(halt) -->
 1324    [ 'halt' ].
 1325prolog_message(break(begin, Level)) -->
 1326    [ 'Break level ~d'-[Level] ].
 1327prolog_message(break(end, Level)) -->
 1328    [ 'Exit break level ~d'-[Level] ].
 1329prolog_message(var_query(_)) -->
 1330    [ '... 1,000,000 ............ 10,000,000 years later', nl, nl,
 1331      '~t~8|>> 42 << (last release gives the question)'
 1332    ].
 1333prolog_message(close_on_abort(Stream)) -->
 1334    [ 'Abort: closed stream ~p'-[Stream] ].
 1335prolog_message(cancel_halt(Reason)) -->
 1336    [ 'Halt cancelled: ~p'-[Reason] ].
 1337prolog_message(on_error(halt(Status))) -->
 1338    { statistics(errors, Errors),
 1339      statistics(warnings, Warnings)
 1340    },
 1341    [ 'Halting with status ~w due to ~D errors and ~D warnings'-
 1342      [Status, Errors, Warnings] ].
 1343
 1344prolog_message(query(QueryResult)) -->
 1345    query_result(QueryResult).
 1346
 1347query_result(no) -->            % failure
 1348    [ ansi(truth(false), 'false.', []) ],
 1349    extra_line.
 1350query_result(yes(true, [])) -->      % prompt_alternatives_on: groundness
 1351    !,
 1352    [ ansi(truth(true), 'true.', []) ],
 1353    extra_line.
 1354query_result(yes(Delays, Residuals)) -->
 1355    result([], Delays, Residuals),
 1356    extra_line.
 1357query_result(done) -->          % user typed <CR>
 1358    extra_line.
 1359query_result(yes(Bindings, Delays, Residuals)) -->
 1360    result(Bindings, Delays, Residuals),
 1361    prompt(yes, Bindings, Delays, Residuals).
 1362query_result(more(Bindings, Delays, Residuals)) -->
 1363    result(Bindings, Delays, Residuals),
 1364    prompt(more, Bindings, Delays, Residuals).
 1365:- if(current_prolog_flag(emscripten, true)). 1366query_result(help) -->
 1367    [ ansi(bold, '  Possible actions:', []), nl,
 1368      '  ; (n,r,space): redo              | t:       trace&redo'-[], nl,
 1369      '  *:             show choicepoint  | . (c,a): stop'-[], nl,
 1370      '  w:             write             | p:       print'-[], nl,
 1371      '  +:             max_depth*5       | -:       max_depth//5'-[], nl,
 1372      '  h (?):         help'-[],
 1373      nl, nl
 1374    ].
 1375:- else. 1376query_result(help) -->
 1377    [ ansi(bold, '  Possible actions:', []), nl,
 1378      '  ; (n,r,space,TAB): redo              | t:           trace&redo'-[], nl,
 1379      '  *:                 show choicepoint  | . (c,a,RET): stop'-[], nl,
 1380      '  w:                 write             | p:           print'-[], nl,
 1381      '  +:                 max_depth*5       | -:           max_depth//5'-[], nl,
 1382      '  b:                 break             | h (?):       help'-[],
 1383      nl, nl
 1384    ].
 1385:- endif. 1386query_result(action) -->
 1387    [ 'Action? '-[], flush ].
 1388query_result(confirm) -->
 1389    [ 'Please answer \'y\' or \'n\'? '-[], flush ].
 1390query_result(eof) -->
 1391    [ nl ].
 1392query_result(toplevel_open_line) -->
 1393    [].
 1394
 1395prompt(Answer, [], true, []-[]) -->
 1396    !,
 1397    prompt(Answer, empty).
 1398prompt(Answer, _, _, _) -->
 1399    !,
 1400    prompt(Answer, non_empty).
 1401
 1402prompt(yes, empty) -->
 1403    !,
 1404    [ ansi(truth(true), 'true.', []) ],
 1405    extra_line.
 1406prompt(yes, _) -->
 1407    !,
 1408    [ full_stop ],
 1409    extra_line.
 1410prompt(more, empty) -->
 1411    !,
 1412    [ ansi(truth(true), 'true ', []), flush ].
 1413prompt(more, _) -->
 1414    !,
 1415    [ ' '-[], flush ].
 1416
 1417result(Bindings, Delays, Residuals) -->
 1418    { current_prolog_flag(answer_write_options, Options0),
 1419      Options = [partial(true)|Options0],
 1420      GOptions = [priority(999)|Options0]
 1421    },
 1422    wfs_residual_program(Delays, GOptions),
 1423    bindings(Bindings, [priority(699)|Options]),
 1424    (   {Residuals == []-[]}
 1425    ->  bind_delays_sep(Bindings, Delays),
 1426        delays(Delays, GOptions)
 1427    ;   bind_res_sep(Bindings, Residuals),
 1428        residuals(Residuals, GOptions),
 1429        (   {Delays == true}
 1430        ->  []
 1431        ;   [','-[], nl],
 1432            delays(Delays, GOptions)
 1433        )
 1434    ).
 1435
 1436bindings([], _) -->
 1437    [].
 1438bindings([binding(Names,Skel,Subst)|T], Options) -->
 1439    { '$last'(Names, Name) },
 1440    var_names(Names), value(Name, Skel, Subst, Options),
 1441    (   { T \== [] }
 1442    ->  [ ','-[], nl ],
 1443        bindings(T, Options)
 1444    ;   []
 1445    ).
 1446
 1447var_names([Name]) -->
 1448    !,
 1449    [ '~w = '-[Name] ].
 1450var_names([Name1,Name2|T]) -->
 1451    !,
 1452    [ '~w = ~w, '-[Name1, Name2] ],
 1453    var_names([Name2|T]).
 1454
 1455
 1456value(Name, Skel, Subst, Options) -->
 1457    (   { var(Skel), Subst = [Skel=S] }
 1458    ->  { Skel = '$VAR'(Name) },
 1459        [ '~W'-[S, Options] ]
 1460    ;   [ '~W'-[Skel, Options] ],
 1461        substitution(Subst, Options)
 1462    ).
 1463
 1464substitution([], _) --> !.
 1465substitution([N=V|T], Options) -->
 1466    [ ', ', ansi(comment, '% where', []), nl,
 1467      '    ~w = ~W'-[N,V,Options] ],
 1468    substitutions(T, Options).
 1469
 1470substitutions([], _) --> [].
 1471substitutions([N=V|T], Options) -->
 1472    [ ','-[], nl, '    ~w = ~W'-[N,V,Options] ],
 1473    substitutions(T, Options).
 1474
 1475
 1476residuals(Normal-Hidden, Options) -->
 1477    residuals1(Normal, Options),
 1478    bind_res_sep(Normal, Hidden),
 1479    (   {Hidden == []}
 1480    ->  []
 1481    ;   [ansi(comment, '% with pending residual goals', []), nl]
 1482    ),
 1483    residuals1(Hidden, Options).
 1484
 1485residuals1([], _) -->
 1486    [].
 1487residuals1([G|Gs], Options) -->
 1488    (   { Gs \== [] }
 1489    ->  [ '~W,'-[G, Options], nl ],
 1490        residuals1(Gs, Options)
 1491    ;   [ '~W'-[G, Options] ]
 1492    ).
 1493
 1494wfs_residual_program(true, _Options) -->
 1495    !.
 1496wfs_residual_program(Goal, _Options) -->
 1497    { current_prolog_flag(toplevel_list_wfs_residual_program, true),
 1498      '$current_typein_module'(TypeIn),
 1499      (   current_predicate(delays_residual_program/2)
 1500      ->  true
 1501      ;   use_module(library(wfs), [delays_residual_program/2])
 1502      ),
 1503      delays_residual_program(TypeIn:Goal, TypeIn:Program),
 1504      Program \== []
 1505    },
 1506    !,
 1507    [ ansi(comment, '% WFS residual program', []), nl ],
 1508    [ ansi(wfs(residual_program), '~@', ['$messages':list_clauses(Program)]) ].
 1509wfs_residual_program(_, _) --> [].
 1510
 1511delays(true, _Options) -->
 1512    !.
 1513delays(Goal, Options) -->
 1514    { current_prolog_flag(toplevel_list_wfs_residual_program, true)
 1515    },
 1516    !,
 1517    [ ansi(truth(undefined), '~W', [Goal, Options]) ].
 1518delays(_, _Options) -->
 1519    [ ansi(truth(undefined), undefined, []) ].
 1520
 1521:- public list_clauses/1. 1522
 1523list_clauses([]).
 1524list_clauses([H|T]) :-
 1525    (   system_undefined(H)
 1526    ->  true
 1527    ;   portray_clause(user_output, H, [indent(4)])
 1528    ),
 1529    list_clauses(T).
 1530
 1531system_undefined((undefined :- tnot(undefined))).
 1532system_undefined((answer_count_restraint :- tnot(answer_count_restraint))).
 1533system_undefined((radial_restraint :- tnot(radial_restraint))).
 1534
 1535bind_res_sep(_, []) --> !.
 1536bind_res_sep(_, []-[]) --> !.
 1537bind_res_sep([], _) --> !.
 1538bind_res_sep(_, _) --> [','-[], nl].
 1539
 1540bind_delays_sep([], _) --> !.
 1541bind_delays_sep(_, true) --> !.
 1542bind_delays_sep(_, _) --> [','-[], nl].
 1543
 1544extra_line -->
 1545    { current_prolog_flag(toplevel_extra_white_line, true) },
 1546    !,
 1547    ['~N'-[]].
 1548extra_line -->
 1549    [].
 1550
 1551prolog_message(if_tty(Message)) -->
 1552    (   {current_prolog_flag(tty_control, true)}
 1553    ->  [ at_same_line ], list(Message)
 1554    ;   []
 1555    ).
 1556prolog_message(halt(Reason)) -->
 1557    [ '~w: halt'-[Reason] ].
 1558prolog_message(no_action(Char)) -->
 1559    [ 'Unknown action: ~c (h for help)'-[Char], nl ].
 1560
 1561prolog_message(history(help(Show, Help))) -->
 1562    [ 'History Commands:', nl,
 1563      '    !!.              Repeat last query', nl,
 1564      '    !nr.             Repeat query numbered <nr>', nl,
 1565      '    !str.            Repeat last query starting with <str>', nl,
 1566      '    !?str.           Repeat last query holding <str>', nl,
 1567      '    ^old^new.        Substitute <old> into <new> of last query', nl,
 1568      '    !nr^old^new.     Substitute in query numbered <nr>', nl,
 1569      '    !str^old^new.    Substitute in query starting with <str>', nl,
 1570      '    !?str^old^new.   Substitute in query holding <str>', nl,
 1571      '    ~w.~21|Show history list'-[Show], nl,
 1572      '    ~w.~21|Show this list'-[Help], nl, nl
 1573    ].
 1574prolog_message(history(no_event)) -->
 1575    [ '! No such event' ].
 1576prolog_message(history(bad_substitution)) -->
 1577    [ '! Bad substitution' ].
 1578prolog_message(history(expanded(Event))) -->
 1579    [ '~w.'-[Event] ].
 1580prolog_message(history(history(Events))) -->
 1581    history_events(Events).
 1582prolog_message(history(no_history)) -->
 1583    [ '! event history not supported in this version' ].
 1584
 1585history_events([]) -->
 1586    [].
 1587history_events([Nr-Event|T]) -->
 1588    [ ansi(comment, '%', []),
 1589      ansi(bold, '~t~w ~6|', [Nr]),
 1590      ansi(code, '~s', [Event]),
 1591      nl
 1592    ],
 1593    history_events(T).