1/*  Part of SWI-Prolog
    2
    3    Author:        Jan Wielemaker
    4    E-mail:        jan@swi-prolog.org
    5    WWW:           https://www.swi-prolog.org
    6    Copyright (c)  1997-2026, 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('$messages',
   39          [ print_message/2,            % +Kind, +Term
   40            print_message_lines/3,      % +Stream, +Prefix, +Lines
   41            message_to_string/2         % +Term, -String
   42          ]).   43
   44:- multifile
   45    prolog:message//1,              % entire message
   46    prolog:error_message//1,        % 1-st argument of error term
   47    prolog:message_context//1,      % Context of error messages
   48    prolog:deprecated//1,	    % Deprecated features
   49    prolog:message_location//1,     % (File) location of error messages
   50    prolog:message_line_element/2,  % Extend printing
   51    prolog:message_action/2.        % Side effects (broadcast)
   52:- dynamic
   53    prolog:message_action/2.        % Allow overruling
   54:- '$hide'((
   55    prolog:message//1,
   56    prolog:error_message//1,
   57    prolog:message_context//1,
   58    prolog:deprecated//1,
   59    prolog:message_location//1,
   60    prolog:message_line_element/2)).   61% Lang, Term versions
   62:- multifile
   63    prolog:message//2,              % entire message
   64    prolog:error_message//2,        % 1-st argument of error term
   65    prolog:message_context//2,      % Context of error messages
   66    prolog:message_location//2,	    % (File) location of error messages
   67    prolog:deprecated//2.	    % Deprecated features
   68:- '$hide'((
   69    prolog:message//2,
   70    prolog:error_message//2,
   71    prolog:message_context//2,
   72    prolog:deprecated//2,
   73    prolog:message_location//2)).   74
   75:- discontiguous
   76    prolog_message/3.   77
   78:- public
   79    translate_message//1,           % +Message (deprecated)
   80    prolog:translate_message//1.    % +Message
   81
   82:- 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.

  106prolog:translate_message(Term) -->
  107    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.

  114translate_message(Term) -->
  115    { nonvar(Term) },
  116    (   { message_lang(Lang) },
  117        prolog:message(Lang, Term)
  118    ;   prolog:message(Term)
  119    ),
  120    !.
  121translate_message(Term) -->
  122    { nonvar(Term) },
  123    translate_message2(Term),
  124    !.
  125translate_message(Term) -->
  126    { nonvar(Term),
  127      Term = error(_, _)
  128    },
  129    [ 'Unknown exception: ~p'-[Term] ].
  130translate_message(Term) -->
  131    [ 'Unknown message: ~p'-[Term] ].
  132
  133translate_message2(Term) -->
  134    prolog_message(Term).
  135translate_message2(error(resource_error(stack), Context)) -->
  136    !,
  137    out_of_stack(Context).
  138translate_message2(error(resource_error(tripwire(Wire, Context)), _)) -->
  139    !,
  140    tripwire_message(Wire, Context).
  141translate_message2(error(existence_error(reset, Ball), SWI)) -->
  142    swi_location(SWI),
  143    tabling_existence_error(Ball, SWI).
  144translate_message2(error(ISO, SWI)) -->
  145    swi_location(SWI),
  146    term_message(ISO),
  147    swi_extra(SWI).
  148translate_message2(unwind(Term)) -->
  149    unwind_message(Term).
  150translate_message2(message_lines(Lines), L, T) :- % deal with old C-warning()
  151    make_message_lines(Lines, L, T).
  152translate_message2(format(Fmt, Args)) -->
  153    [ Fmt-Args ].
  154
  155make_message_lines([], T, T) :- !.
  156make_message_lines([Last],  ['~w'-[Last]|T], T) :- !.
  157make_message_lines([L0|LT], ['~w'-[L0],nl|T0], T) :-
  158    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.

  166:- public term_message//1.  167term_message(Term) -->
  168    {var(Term)},
  169    !,
  170    [ 'Unknown error term: ~p'-[Term] ].
  171term_message(Term) -->
  172    { message_lang(Lang) },
  173    prolog:error_message(Lang, Term),
  174    !.
  175term_message(Term) -->
  176    prolog:error_message(Term),
  177    !.
  178term_message(Term) -->
  179    iso_message(Term).
  180term_message(Term) -->
  181    swi_message(Term).
  182term_message(Term) -->
  183    [ 'Unknown error term: ~p'-[Term] ].
  184
  185iso_message(resource_error(c_stack)) -->
  186    out_of_c_stack.
  187iso_message(resource_error(Missing)) -->
  188    [ 'Not enough resources: ~w'-[Missing] ].
  189iso_message(type_error(evaluable, Actual)) -->
  190    { callable(Actual) },
  191    [ 'Arithmetic: `~p'' is not a function'-[Actual] ].
  192iso_message(type_error(free_of_attvar, Actual)) -->
  193    [ 'Type error: `~W'' contains attributed variables'-
  194      [Actual,[portray(true), attributes(portray)]] ].
  195iso_message(type_error(Expected, Actual)) -->
  196    [ 'Type error: `~w'' expected, found `~p'''-[Expected, Actual] ],
  197    type_error_comment(Expected, Actual).
  198iso_message(domain_error(Domain, Actual)) -->
  199    [ 'Domain error: '-[] ], domain(Domain),
  200    [ ' expected, found `~p'''-[Actual] ].
  201iso_message(instantiation_error) -->
  202    [ 'Arguments are not sufficiently instantiated' ].
  203iso_message(uninstantiation_error(Var)) -->
  204    [ 'Uninstantiated argument expected, found ~p'-[Var] ].
  205iso_message(representation_error(What)) -->
  206    [ 'Cannot represent due to `~w'''-[What] ].
  207iso_message(permission_error(Action, Type, Object)) -->
  208    permission_error(Action, Type, Object).
  209iso_message(evaluation_error(Which)) -->
  210    [ 'Arithmetic: evaluation error: `~p'''-[Which] ].
  211iso_message(existence_error(procedure, Proc)) -->
  212    [ 'Unknown procedure: ~q'-[Proc] ],
  213    unknown_proc_msg(Proc).
  214iso_message(existence_error(answer_variable, Var)) -->
  215    [ '$~w was not bound by a previous query'-[Var] ].
  216iso_message(existence_error(matching_rule, Goal)) -->
  217    [ 'No rule matches ~p'-[Goal] ].
  218iso_message(existence_error(Type, Object)) -->
  219    [ '~w `~p'' does not exist'-[Type, Object] ].
  220iso_message(existence_error(export, PI, module(M))) --> % not ISO
  221    [ 'Module ', ansi(code, '~q', [M]), ' does not export ',
  222      ansi(code, '~q', [PI]) ].
  223iso_message(existence_error(Type, Object, In)) --> % not ISO
  224    [ '~w `~p'' does not exist in ~p'-[Type, Object, In] ].
  225iso_message(busy(Type, Object)) -->
  226    [ '~w `~p'' is busy'-[Type, Object] ].
  227iso_message(syntax_error(swi_backslash_newline)) -->
  228    [ 'Deprecated: ... \\<newline><white>*.  Use \\c' ].
  229iso_message(syntax_error(warning_var_tag)) -->
  230    [ 'Deprecated: dict with unbound tag (_{...}).  Mapped to #{...}.' ].
  231iso_message(syntax_error(var_tag)) -->
  232    [ 'Syntax error: dict syntax with unbound tag (_{...}).' ].
  233iso_message(syntax_error(Id)) -->
  234    [ 'Syntax error: ' ],
  235    syntax_error(Id).
  236iso_message(occurs_check(Var, In)) -->
  237    [ '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.

  244permission_error(Action, built_in_procedure, Pred) -->
  245    { user_predicate_indicator(Pred, PI)
  246    },
  247    [ 'No permission to ~w built-in predicate `~p'''-[Action, PI] ],
  248    (   {Action \== export}
  249    ->  [ nl,
  250          'Use :- redefine_system_predicate(+Head) if redefinition is intended'
  251        ]
  252    ;   []
  253    ).
  254permission_error(import_into(Dest), procedure, Pred) -->
  255    [ 'No permission to import ~p into ~w'-[Pred, Dest] ].
  256permission_error(Action, static_procedure, Proc) -->
  257    [ 'No permission to ~w static procedure `~p'''-[Action, Proc] ],
  258    defined_definition('Defined', Proc).
  259permission_error(input, stream, Stream) -->
  260    [ 'No permission to read from output stream `~p'''-[Stream] ].
  261permission_error(output, stream, Stream) -->
  262    [ 'No permission to write to input stream `~p'''-[Stream] ].
  263permission_error(input, text_stream, Stream) -->
  264    [ 'No permission to read bytes from TEXT stream `~p'''-[Stream] ].
  265permission_error(output, text_stream, Stream) -->
  266    [ 'No permission to write bytes to TEXT stream `~p'''-[Stream] ].
  267permission_error(input, binary_stream, Stream) -->
  268    [ 'No permission to read characters from binary stream `~p'''-[Stream] ].
  269permission_error(output, binary_stream, Stream) -->
  270    [ 'No permission to write characters to binary stream `~p'''-[Stream] ].
  271permission_error(open, source_sink, alias(Alias)) -->
  272    [ 'No permission to reuse alias "~p": already taken'-[Alias] ].
  273permission_error(tnot, non_tabled_procedure, Pred) -->
  274    [ 'The argument of tnot/1 is not tabled: ~p'-[Pred] ].
  275permission_error(assert, procedure, Pred) -->
  276    { '$pi_head'(Pred, Head),
  277      predicate_property(Head, ssu)
  278    },
  279    [ '~p: an SSU (Head => Body) predicate cannot have normal Prolog clauses'-
  280      [Pred] ].
  281permission_error(Action, Type, Object) -->
  282    [ 'No permission to ~w ~w `~p'''-[Action, Type, Object] ].
  283
  284
  285unknown_proc_msg(_:(^)/2) -->
  286    !,
  287    unknown_proc_msg((^)/2).
  288unknown_proc_msg((^)/2) -->
  289    !,
  290    [nl, '  ^/2 can only appear as the 2nd argument of setof/3 and bagof/3'].
  291unknown_proc_msg((:-)/2) -->
  292    !,
  293    [nl, '  Rules must be loaded from a file'],
  294    faq('ToplevelMode').
  295unknown_proc_msg((=>)/2) -->
  296    !,
  297    [nl, '  Rules must be loaded from a file'],
  298    faq('ToplevelMode').
  299unknown_proc_msg((:-)/1) -->
  300    !,
  301    [nl, '  Directives must be loaded from a file'],
  302    faq('ToplevelMode').
  303unknown_proc_msg((?-)/1) -->
  304    !,
  305    [nl, '  ?- is the Prolog prompt'],
  306    faq('ToplevelMode').
  307unknown_proc_msg(Proc) -->
  308    { dwim_predicates(Proc, Dwims) },
  309    (   {Dwims \== []}
  310    ->  [nl, '  However, there are definitions for:', nl],
  311        dwim_message(Dwims)
  312    ;   []
  313    ).
  314
  315dependency_error(shared(Shared), private(Private)) -->
  316    [ 'Shared table for ~p may not depend on private ~p'-[Shared, Private] ].
  317dependency_error(Dep, monotonic(On)) -->
  318    { '$pi_head'(PI, Dep),
  319      '$pi_head'(MPI, On)
  320    },
  321    [ 'Dependent ~p on monotonic predicate ~p is not monotonic or incremental'-
  322      [PI, MPI]
  323    ].
  324
  325faq(Page) -->
  326    [nl, '  See FAQ at https://www.swi-prolog.org/FAQ/', Page, '.html' ].
  327
  328type_error_comment(_Expected, Actual) -->
  329    { type_of(Actual, Type),
  330      (   sub_atom(Type, 0, 1, _, First),
  331          memberchk(First, [a,e,i,o,u])
  332      ->  Article = an
  333      ;   Article = a
  334      )
  335    },
  336    [ ' (~w ~w)'-[Article, Type] ].
  337
  338type_of(Term, Type) :-
  339    (   attvar(Term)      -> Type = attvar
  340    ;   var(Term)         -> Type = var
  341    ;   atom(Term)        -> Type = atom
  342    ;   integer(Term)     -> Type = integer
  343    ;   string(Term)      -> Type = string
  344    ;   Term == []        -> Type = empty_list
  345    ;   blob(Term, BlobT) -> blob_type(BlobT, Type)
  346    ;   rational(Term)    -> Type = rational
  347    ;   float(Term)       -> Type = float
  348    ;   is_stream(Term)   -> Type = stream
  349    ;   is_dict(Term)     -> Type = dict
  350    ;   is_list(Term)     -> Type = list
  351    ;   Term = [_|_]      -> list_like(Term, Type)
  352    ;   cyclic_term(Term) -> Type = cyclic
  353    ;   compound(Term)    -> Type = compound
  354    ;                        Type = unknown
  355    ).
  356
  357list_like(Term, Type) :-
  358    '$skip_list'(_, Term, Tail),
  359    (   var(Tail)
  360    ->  Type = partial_list
  361    ;   Type = invalid_list                      % TBD: Better name?
  362    ).
  363
  364blob_type(BlobT, Type) :-
  365    atom_concat(BlobT, '_reference', Type).
  366
  367syntax_error(end_of_clause) -->
  368    [ 'Unexpected end of clause' ].
  369syntax_error(end_of_clause_expected) -->
  370    [ 'End of clause expected' ].
  371syntax_error(end_of_file) -->
  372    [ 'Unexpected end of file' ].
  373syntax_error(end_of_file_in_block_comment) -->
  374    [ 'End of file in /* ... */ comment' ].
  375syntax_error(end_of_file_in_quoted(Quote)) -->
  376    [ 'End of file in quoted ' ],
  377    quoted_type(Quote).
  378syntax_error(illegal_number) -->
  379    [ 'Illegal number' ].
  380syntax_error(long_atom) -->
  381    [ 'Atom too long (see style_check/1)' ].
  382syntax_error(long_string) -->
  383    [ 'String too long (see style_check/1)' ].
  384syntax_error(operator_clash) -->
  385    [ 'Operator priority clash' ].
  386syntax_error(operator_expected) -->
  387    [ 'Operator expected' ].
  388syntax_error(operator_balance) -->
  389    [ 'Unbalanced operator' ].
  390syntax_error(quoted_punctuation) -->
  391    [ 'Operand expected, unquoted comma or bar found' ].
  392syntax_error(list_rest) -->
  393    [ 'Unexpected comma or bar in rest of list' ].
  394syntax_error(cannot_start_term) -->
  395    [ 'Illegal start of term' ].
  396syntax_error(punct(Punct, End)) -->
  397    [ 'Unexpected `~w\' before `~w\''-[Punct, End] ].
  398syntax_error(undefined_char_escape(C)) -->
  399    [ 'Unknown character escape in quoted atom or string: `\\~w\''-[C] ].
  400syntax_error(void_not_allowed) -->
  401    [ 'Empty argument list "()"' ].
  402syntax_error(Term) -->
  403    { compound(Term),
  404      compound_name_arguments(Term, Syntax, [Text])
  405    }, !,
  406    [ '~w expected, found '-[Syntax], ansi(code, '"~w"', [Text]) ].
  407syntax_error(Message) -->
  408    [ '~w'-[Message] ].
  409
  410quoted_type('\'') --> [atom].
  411quoted_type('\"') --> { current_prolog_flag(double_quotes, Type) }, [Type-[]].
  412quoted_type('\`') --> { current_prolog_flag(back_quotes, Type) }, [Type-[]].
  413
  414domain(range(Low,High)) -->
  415    !,
  416    ['[~q..~q]'-[Low,High] ].
  417domain(Domain) -->
  418    ['`~w\''-[Domain] ].

 tabling_existence_error(+Ball, +Context)//

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

  425tabling_existence_error(Ball, Context) -->
  426    { table_shift_ball(Ball) },
  427    [ 'Tabling dependency error' ],
  428    swi_extra(Context).
  429
  430table_shift_ball(dependency(_Head)).
  431table_shift_ball(dependency(_Skeleton, _Trie, _Mono)).
  432table_shift_ball(call_info(_Skeleton, _Status)).
  433table_shift_ball(call_info(_GenSkeleton, _Skeleton, _Status)).

 dwim_predicates(+PI, -Dwims)

Find related predicate indicators.

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

 swi_location(+Term)// is det

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

  555:- public swi_location//1.  556swi_location(X) -->
  557    { var(X) },
  558    !.
  559swi_location(Context) -->
  560    { message_lang(Lang) },
  561    prolog:message_location(Lang, Context),
  562    !.
  563swi_location(Context) -->
  564    prolog:message_location(Context),
  565    !.
  566swi_location(context(Caller, _Msg)) -->
  567    { ground(Caller) },
  568    !,
  569    caller(Caller).
  570swi_location(file(Path, Line, -1, _CharNo)) -->
  571    !,
  572    [ url(Path:Line), ': ' ].
  573swi_location(file(Path, Line, LinePos, _CharNo)) -->
  574    [ url(Path:Line:LinePos), ': ' ].
  575swi_location(stream(Stream, Line, LinePos, CharNo)) -->
  576    (   { is_stream(Stream),
  577          stream_property(Stream, file_name(File))
  578        }
  579    ->  swi_location(file(File, Line, LinePos, CharNo))
  580    ;   [ 'Stream ~w:~d:~d '-[Stream, Line, LinePos] ]
  581    ).
  582swi_location(autoload(File:Line)) -->
  583    [ url(File:Line), ': ' ].
  584swi_location(_) -->
  585    [].
  586
  587caller(system:'$record_clause'/3) -->
  588    !,
  589    [].
  590caller(Module:Name/Arity) -->
  591    !,
  592    (   { \+ hidden_module(Module) }
  593    ->  [ '~q:~q/~w: '-[Module, Name, Arity] ]
  594    ;   [ '~q/~w: '-[Name, Arity] ]
  595    ).
  596caller(Name/Arity) -->
  597    [ '~q/~w: '-[Name, Arity] ].
  598caller(Caller) -->
  599    [ '~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.

  610swi_extra(X) -->
  611    { var(X) },
  612    !,
  613    [].
  614swi_extra(Context) -->
  615    { message_lang(Lang) },
  616    prolog:message_context(Lang, Context),
  617    !.
  618swi_extra(Context) -->
  619    prolog:message_context(Context).
  620swi_extra(context(_, Msg)) -->
  621    { nonvar(Msg),
  622      Msg \== ''
  623    },
  624    !,
  625    swi_comment(Msg).
  626swi_extra(string(String, CharPos)) -->
  627    { sub_string(String, 0, CharPos, _, Before),
  628      sub_string(String, CharPos, _, 0, After)
  629    },
  630    [ nl, '~w'-[Before], nl, '** here **', nl, '~w'-[After] ].
  631swi_extra(_) -->
  632    [].
  633
  634swi_comment(already_from(Module)) -->
  635    !,
  636    [ ' (already imported from ~q)'-[Module] ].
  637swi_comment(directory(_Dir)) -->
  638    !,
  639    [ ' (is a directory)' ].
  640swi_comment(not_a_directory(_Dir)) -->
  641    !,
  642    [ ' (is not a directory)' ].
  643swi_comment(Msg) -->
  644    [ ' (~w)'-[Msg] ].
  645
  646
  647thread_context -->
  648    { \+ current_prolog_flag(toplevel_thread, true),
  649      thread_self(Id)
  650    },
  651    !,
  652    ['[Thread ~w] '-[Id]].
  653thread_context -->
  654    [].
  655
  656		 /*******************************
  657		 *        UNWIND MESSAGES	*
  658		 *******************************/
  659
  660unwind_message(Var) -->
  661    { var(Var) }, !,
  662    [ 'Unknown unwind message: ~p'-[Var] ].
  663unwind_message(abort) -->
  664    [ 'Execution Aborted' ].
  665unwind_message(halt(_)) -->
  666    [].
  667unwind_message(thread_exit(Term)) -->
  668    [ 'Invalid thread_exit/1.  Payload: ~p'-[Term] ].
  669unwind_message(Term) -->
  670    [ 'Unknown "unwind" exception: ~p'-[Term] ].
  671
  672
  673                 /*******************************
  674                 *        NORMAL MESSAGES       *
  675                 *******************************/
  676
  677:- dynamic prolog:version_msg/1.  678:- multifile prolog:version_msg/1.  679
  680prolog_message(welcome) -->
  681    [ 'Welcome to SWI-Prolog (' ],
  682    prolog_message(threads),
  683    prolog_message(address_bits),
  684    ['version ' ],
  685    prolog_message(version),
  686    [ ')', nl ],
  687    prolog_message(copyright),
  688    [ nl ],
  689    translate_message(user_versions),
  690    [ nl ],
  691    prolog_message(documentaton),
  692    [ nl, nl ].
  693prolog_message(user_versions) -->
  694    (   { findall(Msg, prolog:version_msg(Msg), Msgs),
  695          Msgs \== []
  696        }
  697    ->  [nl],
  698        user_version_messages(Msgs)
  699    ;   []
  700    ).
  701prolog_message(deprecated(Term)) -->
  702    { nonvar(Term) },
  703    (   { message_lang(Lang) },
  704        prolog:deprecated(Lang, Term)
  705    ->  []
  706    ;   prolog:deprecated(Term)
  707    ->  []
  708    ;   deprecated(Term)
  709    ).
  710prolog_message(unhandled_exception(E)) -->
  711    { nonvar(E) },
  712    [ 'Unhandled exception: ' ],
  713    (   translate_message(E)
  714    ->  []
  715    ;   [ '~p'-[E] ]
  716    ).

 prolog_message(+Term)//

  720prolog_message(initialization_error(_, E, File:Line)) -->
  721    !,
  722    [ url(File:Line),
  723      ': Initialization goal raised exception:', nl
  724    ],
  725    translate_message(E).
  726prolog_message(initialization_error(Goal, E, _)) -->
  727    [ 'Initialization goal ~p raised exception:'-[Goal], nl ],
  728    translate_message(E).
  729prolog_message(initialization_failure(_Goal, File:Line)) -->
  730    !,
  731    [ url(File:Line),
  732      ': Initialization goal failed'-[]
  733    ].
  734prolog_message(initialization_failure(Goal, _)) -->
  735    [ 'Initialization goal failed: ~p'-[Goal]
  736    ].
  737prolog_message(initialization_exception(E)) -->
  738    [ 'Prolog initialisation failed:', nl ],
  739    translate_message(E).
  740prolog_message(initialization(halt(Status), Goal, File:Line)) -->
  741    [ url(File:Line), ': '], goal(Goal), [nl,
  742      '  Initialization goal called ', ansi(code, '~p', [halt(Status)]),
  743      '.', nl,
  744      '  The program entry point should be called using ',
  745      ansi(code, 'initialization/2', []), '.', nl,
  746      '  Consider using ', ansi(code, 'library(main)', []), '.'
  747    ].
  748prolog_message(init_goal_syntax(Error, Text)) -->
  749    !,
  750    [ '-g ~w: '-[Text] ],
  751    translate_message(Error).
  752prolog_message(init_goal_failed(failed, @(Goal,File:Line))) -->
  753    !,
  754    [ url(File:Line), ': ~p: false'-[Goal] ].
  755prolog_message(init_goal_failed(Error, @(Goal,File:Line))) -->
  756    !,
  757    [ url(File:Line), ': ~p '-[Goal] ],
  758    translate_message(Error).
  759prolog_message(init_goal_failed(failed, Text)) -->
  760    !,
  761    [ '-g ~w: false'-[Text] ].
  762prolog_message(init_goal_failed(Error, Text)) -->
  763    !,
  764    [ '-g ~w: '-[Text] ],
  765    translate_message(Error).
  766prolog_message(goal_failed(Context, Goal)) -->
  767    [ 'Goal (~w) failed: ~p'-[Context, Goal] ].
  768prolog_message(no_current_module(Module)) -->
  769    [ '~w is not a current module (created)'-[Module] ].
  770prolog_message(commandline_arg_type(Flag, Arg)) -->
  771    [ 'Bad argument to commandline option -~w: ~w'-[Flag, Arg] ].
  772prolog_message(missing_feature(Name)) -->
  773    [ 'This version of SWI-Prolog does not support ~w'-[Name] ].
  774prolog_message(singletons(_Term, List)) -->
  775    [ 'Singleton variables: ~w'-[List] ].
  776prolog_message(multitons(_Term, List)) -->
  777    [ 'Singleton-marked variables appearing more than once: ~w'-[List] ].
  778prolog_message(profile_no_cpu_time) -->
  779    [ 'No CPU-time info.  Check the SWI-Prolog manual for details' ].
  780prolog_message(non_ascii(Text, Type)) -->
  781    [ 'Unquoted ~w with non-portable characters: ~w'-[Type, Text] ].
  782prolog_message(io_warning(Stream, Message)) -->
  783    { stream_property(Stream, position(Position)),
  784      !,
  785      stream_position_data(line_count, Position, LineNo),
  786      stream_position_data(line_position, Position, LinePos),
  787      (   stream_property(Stream, file_name(File))
  788      ->  Obj = File
  789      ;   Obj = Stream
  790      )
  791    },
  792    [ '~p:~d:~d: ~w'-[Obj, LineNo, LinePos, Message] ].
  793prolog_message(io_warning(Stream, Message)) -->
  794    [ 'stream ~p: ~w'-[Stream, Message] ].
  795prolog_message(option_usage(pldoc)) -->
  796    [ 'Usage: --pldoc[=port]' ].
  797prolog_message(interrupt(begin)) -->
  798    [ 'Action (h for help) ? ', flush ].
  799prolog_message(interrupt(end)) -->
  800    [ 'continue' ].
  801prolog_message(interrupt(trace)) -->
  802    [ 'continue (trace mode)' ].
  803prolog_message(unknown_in_module_user) -->
  804    [ 'Using a non-error value for unknown in the global module', nl,
  805      'causes most of the development environment to stop working.', nl,
  806      'Please use :- dynamic or limit usage of unknown to a module.', nl,
  807      'See https://www.swi-prolog.org/howto/database.html'
  808    ].
  809prolog_message(untable(PI)) -->
  810    [ 'Reconsult: removed tabling for ~p'-[PI] ].
  811prolog_message(unknown_option(Set, Opt)) -->
  812    [ 'Unknown ~w option: ~p'-[Set, Opt] ].
  813
  814
  815                 /*******************************
  816                 *         LOADING FILES        *
  817                 *******************************/
  818
  819prolog_message(modify_active_procedure(Who, What)) -->
  820    [ '~p: modified active procedure ~p'-[Who, What] ].
  821prolog_message(load_file(failed(user:File))) -->
  822    [ 'Failed to load ~p'-[File] ].
  823prolog_message(load_file(failed(Module:File))) -->
  824    [ 'Failed to load ~p into module ~p'-[File, Module] ].
  825prolog_message(load_file(failed(File))) -->
  826    [ 'Failed to load ~p'-[File] ].
  827prolog_message(mixed_directive(Goal)) -->
  828    [ 'Cannot pre-compile mixed load/call directive: ~p'-[Goal] ].
  829prolog_message(cannot_redefine_comma) -->
  830    [ 'Full stop in clause-body?  Cannot redefine ,/2' ].
  831prolog_message(illegal_autoload_index(Dir, Term)) -->
  832    [ 'Illegal term in INDEX file of directory ~w: ~w'-[Dir, Term] ].
  833prolog_message(redefined_procedure(Type, Proc)) -->
  834    [ 'Redefined ~w procedure ~p'-[Type, Proc] ],
  835    defined_definition('Previously defined', Proc).
  836prolog_message(declare_module(Module, abolish(Predicates))) -->
  837    [ 'Loading module ~w abolished: ~p'-[Module, Predicates] ].
  838prolog_message(import_private(Module, Private)) -->
  839    [ 'import/1: ~p is not exported (still imported into ~q)'-
  840      [Private, Module]
  841    ].
  842prolog_message(ignored_weak_import(Into, From:PI)) -->
  843    [ 'Local definition of ~p overrides weak import from ~q'-
  844      [Into:PI, From]
  845    ].
  846prolog_message(undefined_export(Module, PI)) -->
  847    [ 'Exported procedure ~q:~q is not defined'-[Module, PI] ].
  848prolog_message(no_exported_op(Module, Op)) -->
  849    [ 'Operator ~q:~q is not exported (still defined)'-[Module, Op] ].
  850prolog_message(discontiguous((-)/2,_)) -->
  851    prolog_message(minus_in_identifier).
  852prolog_message(discontiguous(Proc,Current)) -->
  853    [ 'Clauses of ', ansi(code, '~p', [Proc]),
  854      ' are not together in the source-file', nl ],
  855    current_definition(Proc, 'Earlier definition at '),
  856    [ 'Current predicate: ', ansi(code, '~p', [Current]), nl,
  857      'Use ', ansi(code, ':- discontiguous ~p.', [Proc]),
  858      ' to suppress this message'
  859    ].
  860prolog_message(decl_no_effect(Goal)) -->
  861    [ 'Deprecated declaration has no effect: ~p'-[Goal] ].
  862prolog_message(load_file(start(Level, File))) -->
  863    [ '~|~t~*+Loading '-[Level] ],
  864    load_file(File),
  865    [ ' ...' ].
  866prolog_message(include_file(start(Level, File))) -->
  867    [ '~|~t~*+include '-[Level] ],
  868    load_file(File),
  869    [ ' ...' ].
  870prolog_message(include_file(done(Level, File))) -->
  871    [ '~|~t~*+included '-[Level] ],
  872    load_file(File).
  873prolog_message(load_file(done(Level, File, Action, Module, Time, Clauses))) -->
  874    [ '~|~t~*+'-[Level] ],
  875    load_file(File),
  876    [ ' ~w'-[Action] ],
  877    load_module(Module),
  878    [ ' ~2f sec, ~D clauses'-[Time, Clauses] ].
  879prolog_message(dwim_undefined(Goal, Alternatives)) -->
  880    { goal_to_predicate_indicator(Goal, Pred)
  881    },
  882    [ 'Unknown procedure: ~q'-[Pred], nl,
  883      '    However, there are definitions for:', nl
  884    ],
  885    dwim_message(Alternatives).
  886prolog_message(dwim_correct(Into)) -->
  887    [ 'Correct to: ~q? '-[Into], flush ].
  888prolog_message(error(loop_error(Spec), file_search(Used))) -->
  889    [ 'File search: too many levels of indirections on: ~p'-[Spec], nl,
  890      '    Used alias expansions:', nl
  891    ],
  892    used_search(Used).
  893prolog_message(minus_in_identifier) -->
  894    [ 'The "-" character should not be used to separate words in an', nl,
  895      'identifier.  Check the SWI-Prolog FAQ for details.'
  896    ].
  897prolog_message(qlf(removed_after_error(File))) -->
  898    [ 'Removed incomplete QLF file ~w'-[File] ].
  899prolog_message(qlf(recompile(Spec,_Pl,_Qlf,Reason))) -->
  900    [ '~p: recompiling QLF file'-[Spec] ],
  901    qlf_recompile_reason(Reason).
  902prolog_message(qlf(can_not_recompile(Spec,QlfFile,_Reason))) -->
  903    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  904      '\tLoading from source'-[]
  905    ].
  906prolog_message(qlf(system_lib_out_of_date(Spec,QlfFile))) -->
  907    [ '~p: can not recompile "~w" (access denied)'-[Spec, QlfFile], nl,
  908      '\tLoading QlfFile'-[]
  909    ].
  910prolog_message(redefine_module(Module, OldFile, File)) -->
  911    [ 'Module "~q" already loaded from ~w.'-[Module, OldFile], nl,
  912      'Wipe and reload from ~w? '-[File], flush
  913    ].
  914prolog_message(redefine_module_reply) -->
  915    [ 'Please answer y(es), n(o) or a(bort)' ].
  916prolog_message(reloaded_in_module(Absolute, OldContext, LM)) -->
  917    [ '~w was previously loaded in module ~w'-[Absolute, OldContext], nl,
  918      '\tnow it is reloaded into module ~w'-[LM] ].
  919prolog_message(expected_layout(Expected, Pos)) -->
  920    [ 'Layout data: expected ~w, found: ~p'-[Expected, Pos] ].
  921
  922defined_definition(Message, Spec) -->
  923    { strip_module(user:Spec, M, Name/Arity),
  924      functor(Head, Name, Arity),
  925      predicate_property(M:Head, file(File)),
  926      predicate_property(M:Head, line_count(Line))
  927    },
  928    !,
  929    [ nl, '~w at '-[Message], url(File:Line) ].
  930defined_definition(_, _) --> [].
  931
  932used_search([]) -->
  933    [].
  934used_search([Alias=Expanded|T]) -->
  935    [ '        file_search_path(~p, ~p)'-[Alias, Expanded], nl ],
  936    used_search(T).
  937
  938load_file(file(Spec, _Path)) -->
  939    (   {atomic(Spec)}
  940    ->  [ '~w'-[Spec] ]
  941    ;   [ '~p'-[Spec] ]
  942    ).
  943%load_file(file(_, Path)) -->
  944%       [ '~w'-[Path] ].
  945
  946load_module(user) --> !.
  947load_module(system) --> !.
  948load_module(Module) -->
  949    [ ' into ~w'-[Module] ].
  950
  951goal_to_predicate_indicator(Goal, PI) :-
  952    strip_module(Goal, Module, Head),
  953    '$pi_head'(PI0, Module:Head),
  954    (   current_predicate(PI0),
  955        predicate_property(Module:Head, non_terminal)
  956    ->  dcg_pi(PI0, PI)
  957    ;   PI = PI0
  958    ),
  959    user_predicate_indicator(PI, PI).
  960
  961dcg_pi(Module:Name/Arity, Module:Name//DCGArity) :-
  962    DCGArity is Arity-2.
  963
  964user_predicate_indicator(Module:PI, PI) :-
  965    hidden_module(Module),
  966    !.
  967user_predicate_indicator(PI, PI).
  968
  969hidden_module(user) :- !.
  970hidden_module(system) :- !.
  971hidden_module(M) :-
  972    sub_atom(M, 0, _, _, $).
  973
  974current_definition(Proc, Prefix) -->
  975    { pi_uhead(Proc, Head),
  976      predicate_property(Head, file(File)),
  977      predicate_property(Head, line_count(Line))
  978    },
  979    [ '~w'-[Prefix], url(File:Line), nl ].
  980current_definition(_, _) --> [].
  981
  982pi_uhead(Module:Name/Arity, Module:Head) :-
  983    !,
  984    atom(Module), atom(Name), integer(Arity),
  985    functor(Head, Name, Arity).
  986pi_uhead(Name/Arity, user:Head) :-
  987    atom(Name), integer(Arity),
  988    functor(Head, Name, Arity).
  989
  990qlf_recompile_reason(old) -->
  991    !,
  992    [ ' (out of date)'-[] ].
  993qlf_recompile_reason(_) -->
  994    [ ' (incompatible with current Prolog version)'-[] ].
  995
  996prolog_message(file_search(cache(Spec, _Cond), Path)) -->
  997    [ 'File search: ~p --> ~p (cache)'-[Spec, Path] ].
  998prolog_message(file_search(found(Spec, Cond), Path)) -->
  999    [ 'File search: ~p --> ~p OK ~p'-[Spec, Path, Cond] ].
 1000prolog_message(file_search(tried(Spec, Cond), Path)) -->
 1001    [ 'File search: ~p --> ~p NO ~p'-[Spec, Path, Cond] ].
 1002
 1003                 /*******************************
 1004                 *              GC              *
 1005                 *******************************/
 1006
 1007prolog_message(agc(start)) -->
 1008    thread_context,
 1009    [ 'AGC: ', flush ].
 1010prolog_message(agc(done(Collected, Remaining, Time))) -->
 1011    [ at_same_line,
 1012      'reclaimed ~D atoms in ~3f sec. (remaining: ~D)'-
 1013      [Collected, Time, Remaining]
 1014    ].
 1015prolog_message(cgc(start)) -->
 1016    thread_context,
 1017    [ 'CGC: ', flush ].
 1018prolog_message(cgc(done(CollectedClauses, _CollectedBytes,
 1019                        RemainingBytes, Time))) -->
 1020    [ at_same_line,
 1021      'reclaimed ~D clauses in ~3f sec. (pending: ~D bytes)'-
 1022      [CollectedClauses, Time, RemainingBytes]
 1023    ].
 1024
 1025		 /*******************************
 1026		 *        STACK OVERFLOW	*
 1027		 *******************************/
 1028
 1029out_of_stack(Context) -->
 1030    { human_stack_size(Context.localused,   Local),
 1031      human_stack_size(Context.globalused,  Global),
 1032      human_stack_size(Context.trailused,   Trail),
 1033      human_stack_size(Context.stack_limit, Limit),
 1034      LCO is (100*(Context.depth - Context.environments))/Context.depth
 1035    },
 1036    [ 'Stack limit (~s) exceeded'-[Limit], nl,
 1037      '  Stack sizes: local: ~s, global: ~s, trail: ~s'-[Local,Global,Trail], nl,
 1038      '  Stack depth: ~D, last-call: ~0f%, Choice points: ~D'-
 1039         [Context.depth, LCO, Context.choicepoints], nl
 1040    ],
 1041    overflow_reason(Context, Resolve),
 1042    resolve_overflow(Resolve).
 1043
 1044human_stack_size(Size, String) :-
 1045    Size < 100,
 1046    format(string(String), '~dKb', [Size]).
 1047human_stack_size(Size, String) :-
 1048    Size < 100 000,
 1049    Value is Size / 1024,
 1050    format(string(String), '~1fMb', [Value]).
 1051human_stack_size(Size, String) :-
 1052    Value is Size / (1024*1024),
 1053    format(string(String), '~1fGb', [Value]).
 1054
 1055overflow_reason(Context, fix) -->
 1056    show_non_termination(Context),
 1057    !.
 1058overflow_reason(Context, enlarge) -->
 1059    { Stack = Context.get(stack) },
 1060    !,
 1061    [ '  In:'-[], nl ],
 1062    stack(Stack).
 1063overflow_reason(_Context, enlarge) -->
 1064    [ '  Insufficient global stack'-[] ].
 1065
 1066show_non_termination(Context) -->
 1067    (   { Stack = Context.get(cycle) }
 1068    ->  [ '  Probable infinite recursion (cycle):'-[], nl ]
 1069    ;   { Stack = Context.get(non_terminating) }
 1070    ->  [ '  Possible non-terminating recursion:'-[], nl ]
 1071    ),
 1072    stack(Stack).
 1073
 1074stack([]) --> [].
 1075stack([frame(Depth, M:Goal, _)|T]) -->
 1076    [ '    [~D] ~q:'-[Depth, M] ],
 1077    stack_goal(Goal),
 1078    [ nl ],
 1079    stack(T).
 1080
 1081stack_goal(Goal) -->
 1082    { compound(Goal),
 1083      !,
 1084      compound_name_arity(Goal, Name, Arity)
 1085    },
 1086    [ '~q('-[Name] ],
 1087    stack_goal_args(1, Arity, Goal),
 1088    [ ')'-[] ].
 1089stack_goal(Goal) -->
 1090    [ '~q'-[Goal] ].
 1091
 1092stack_goal_args(I, Arity, Goal) -->
 1093    { I =< Arity,
 1094      !,
 1095      arg(I, Goal, A),
 1096      I2 is I + 1
 1097    },
 1098    stack_goal_arg(A),
 1099    (   { I2 =< Arity }
 1100    ->  [ ', '-[] ],
 1101        stack_goal_args(I2, Arity, Goal)
 1102    ;   []
 1103    ).
 1104stack_goal_args(_, _, _) -->
 1105    [].
 1106
 1107stack_goal_arg(A) -->
 1108    { nonvar(A),
 1109      A = [Len|T],
 1110      !
 1111    },
 1112    (   {Len == cyclic_term}
 1113    ->  [ '[cyclic list]'-[] ]
 1114    ;   {T == []}
 1115    ->  [ '[length:~D]'-[Len] ]
 1116    ;   [ '[length:~D|~p]'-[Len, T] ]
 1117    ).
 1118stack_goal_arg(A) -->
 1119    { nonvar(A),
 1120      A = _/_,
 1121      !
 1122    },
 1123    [ '<compound ~p>'-[A] ].
 1124stack_goal_arg(A) -->
 1125    [ '~p'-[A] ].
 1126
 1127resolve_overflow(fix) -->
 1128    [].
 1129resolve_overflow(enlarge) -->
 1130    { current_prolog_flag(stack_limit, LimitBytes),
 1131      NewLimit is LimitBytes * 2
 1132    },
 1133    [ nl,
 1134      'Use the --stack_limit=size[KMG] command line option or'-[], nl,
 1135      '?- set_prolog_flag(stack_limit, ~I). to double the limit.'-[NewLimit]
 1136    ].

 out_of_c_stack

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

 1143out_of_c_stack -->
 1144    { statistics(c_stack, Limit), Limit > 0 },
 1145    !,
 1146    [ 'C-stack limit (~D bytes) exceeded.'-[Limit], nl ],
 1147    resolve_c_stack_overflow(Limit).
 1148out_of_c_stack -->
 1149    { statistics(c_stack, Limit), Limit > 0 },
 1150    [ 'C-stack limit exceeded.'-[Limit], nl ],
 1151    resolve_c_stack_overflow(Limit).
 1152
 1153resolve_c_stack_overflow(_Limit) -->
 1154    { thread_self(main) },
 1155    [ 'Use the shell command ' ], code('~w', 'ulimit -s size'),
 1156    [ ' to enlarge the limit.' ].
 1157resolve_c_stack_overflow(_Limit) -->
 1158    [ 'Use the ' ], code('~w', 'c_stack(KBytes)'),
 1159    [ ' option of '], code(thread_create/3), [' to enlarge the limit.' ].
 1160
 1161
 1162                 /*******************************
 1163                 *        MAKE/AUTOLOAD         *
 1164                 *******************************/
 1165
 1166prolog_message(make(reload(Files))) -->
 1167    { length(Files, N)
 1168    },
 1169    [ 'Make: reloading ~D files'-[N] ].
 1170prolog_message(make(done(_Files))) -->
 1171    [ 'Make: finished' ].
 1172prolog_message(make(library_index(Dir))) -->
 1173    [ 'Updating index for library ~w'-[Dir] ].
 1174prolog_message(autoload(Pred, File)) -->
 1175    thread_context,
 1176    [ 'autoloading ~p from ~w'-[Pred, File] ].
 1177prolog_message(autoload(read_index(Dir))) -->
 1178    [ 'Loading autoload index for ~w'-[Dir] ].
 1179prolog_message(autoload(disabled(Loaded))) -->
 1180    [ 'Disabled autoloading (loaded ~D files)'-[Loaded] ].
 1181prolog_message(autoload(already_defined(PI, From))) -->
 1182    code(PI),
 1183    (   { '$pi_head'(PI, Head),
 1184          predicate_property(Head, built_in)
 1185        }
 1186    ->  [' is a built-in predicate']
 1187    ;   [ ' is already imported from module ' ],
 1188        code(From)
 1189    ).
 1190
 1191swi_message(autoload(Msg)) -->
 1192    [ nl, '  ' ],
 1193    autoload_message(Msg).
 1194
 1195autoload_message(not_exported(PI, Spec, _FullFile, _Exports)) -->
 1196    [ ansi(code, '~w', [Spec]),
 1197      ' does not export ',
 1198      ansi(code, '~p', [PI])
 1199    ].
 1200autoload_message(no_file(Spec)) -->
 1201    [ ansi(code, '~p', [Spec]), ': No such file' ].
 1202
 1203
 1204                 /*******************************
 1205                 *       COMPILER WARNINGS      *
 1206                 *******************************/
 1207
 1208% print warnings about dubious code raised by the compiler.
 1209% TBD: pass in PC to produce exact error locations.
 1210
 1211prolog_message(compiler_warnings(Clause, Warnings0)) -->
 1212    {   print_goal_options(DefOptions),
 1213        (   prolog_load_context(variable_names, VarNames)
 1214        ->  warnings_with_named_vars(Warnings0, VarNames, Warnings),
 1215            Options = [variable_names(VarNames)|DefOptions]
 1216        ;   Options = DefOptions,
 1217            Warnings = Warnings0
 1218        )
 1219    },
 1220    compiler_warnings(Warnings, Clause, Options).
 1221
 1222warnings_with_named_vars([], _, []).
 1223warnings_with_named_vars([H|T0], VarNames, [H|T]) :-
 1224    term_variables(H, Vars),
 1225    '$member'(V1, Vars),
 1226    '$member'(_=V2, VarNames),
 1227    V1 == V2,
 1228    !,
 1229    warnings_with_named_vars(T0, VarNames, T).
 1230warnings_with_named_vars([_|T0], VarNames, T) :-
 1231    warnings_with_named_vars(T0, VarNames, T).
 1232
 1233
 1234compiler_warnings([], _, _) --> [].
 1235compiler_warnings([H|T], Clause, Options) -->
 1236    (   compiler_warning(H, Clause, Options)
 1237    ->  []
 1238    ;   [ 'Unknown compiler warning: ~W'-[H,Options] ]
 1239    ),
 1240    (   {T==[]}
 1241    ->  []
 1242    ;   [nl]
 1243    ),
 1244    compiler_warnings(T, Clause, Options).
 1245
 1246compiler_warning(eq_vv(A,B), _Clause, Options) -->
 1247    (   { A == B }
 1248    ->  [ 'Test is always true: ~W'-[A==B, Options] ]
 1249    ;   [ 'Test is always false: ~W'-[A==B, Options] ]
 1250    ).
 1251compiler_warning(eq_singleton(A,B), _Clause, Options) -->
 1252    [ 'Test is always false: ~W'-[A==B, Options] ].
 1253compiler_warning(neq_vv(A,B), _Clause, Options) -->
 1254    (   { A \== B }
 1255    ->  [ 'Test is always true: ~W'-[A\==B, Options] ]
 1256    ;   [ 'Test is always false: ~W'-[A\==B, Options] ]
 1257    ).
 1258compiler_warning(neq_singleton(A,B), _Clause, Options) -->
 1259    [ 'Test is always true: ~W'-[A\==B, Options] ].
 1260compiler_warning(unify_singleton(A,B), _Clause, Options) -->
 1261    [ 'Unified variable is not used: ~W'-[A=B, Options] ].
 1262compiler_warning(always(Bool, Pred, Arg), _Clause, Options) -->
 1263    { Goal =.. [Pred,Arg] },
 1264    [ 'Test is always ~w: ~W'-[Bool, Goal, Options] ].
 1265compiler_warning(unbalanced_var(V), _Clause, Options) -->
 1266    [ 'Variable not introduced in all branches: ~W'-[V, Options] ].
 1267compiler_warning(branch_singleton(V), _Clause, Options) -->
 1268    [ 'Singleton variable in branch: ~W'-[V, Options] ].
 1269compiler_warning(negation_singleton(V), _Clause, Options) -->
 1270    [ 'Singleton variable in \\+: ~W'-[V, Options] ].
 1271compiler_warning(multiton(V), _Clause, Options) -->
 1272    [ 'Singleton-marked variable appears more than once: ~W'-[V, Options] ].
 1273
 1274print_goal_options(
 1275    [ quoted(true),
 1276      portray(true)
 1277    ]).
 1278
 1279
 1280                 /*******************************
 1281                 *      TOPLEVEL MESSAGES       *
 1282                 *******************************/
 1283
 1284prolog_message(version) -->
 1285    { current_prolog_flag(version_git, Version) },
 1286    !,
 1287    [ '~w'-[Version] ].
 1288prolog_message(version) -->
 1289    { current_prolog_flag(version_data, swi(Major,Minor,Patch,Options))
 1290    },
 1291    (   { memberchk(tag(Tag), Options) }
 1292    ->  [ '~w.~w.~w-~w'-[Major, Minor, Patch, Tag] ]
 1293    ;   [ '~w.~w.~w'-[Major, Minor, Patch] ]
 1294    ).
 1295prolog_message(address_bits) -->
 1296    { current_prolog_flag(address_bits, Bits)
 1297    },
 1298    !,
 1299    [ '~d bits, '-[Bits] ].
 1300prolog_message(threads) -->
 1301    { current_prolog_flag(threads, true)
 1302    },
 1303    !,
 1304    [ 'threaded, ' ].
 1305prolog_message(threads) -->
 1306    [].
 1307prolog_message(copyright) -->
 1308    [ 'SWI-Prolog comes with ABSOLUTELY NO WARRANTY. This is free software.', nl,
 1309      'Please run ', ansi(code, '?- license.', []), ' for legal details.'
 1310    ].
 1311prolog_message(documentaton) -->
 1312    [ 'For online help and background, visit ', url('https://www.swi-prolog.org') ],
 1313    (   { exists_source(library(help)) }
 1314    ->  [ nl,
 1315          'For built-in help, use ', ansi(code, '?- help(Topic).', []),
 1316          ' or ', ansi(code, '?- apropos(Word).', [])
 1317        ]
 1318    ;   []
 1319    ).
 1320prolog_message(about) -->
 1321    [ 'SWI-Prolog version (' ],
 1322    prolog_message(threads),
 1323    prolog_message(address_bits),
 1324    ['version ' ],
 1325    prolog_message(version),
 1326    [ ')', nl ],
 1327    prolog_message(copyright).
 1328prolog_message(halt) -->
 1329    [ 'halt' ].
 1330prolog_message(break(begin, Level)) -->
 1331    [ 'Break level ~d'-[Level] ].
 1332prolog_message(break(end, Level)) -->
 1333    [ 'Exit break level ~d'-[Level] ].
 1334prolog_message(var_query(_)) -->
 1335    [ '... 1,000,000 ............ 10,000,000 years later', nl, nl,
 1336      '~t~8|>> 42 << (last release gives the question)'
 1337    ].
 1338prolog_message(close_on_abort(Stream)) -->
 1339    [ 'Abort: closed stream ~p'-[Stream] ].
 1340prolog_message(cancel_halt(Reason)) -->
 1341    [ 'Halt cancelled: ~p'-[Reason] ].
 1342prolog_message(on_error(halt(Status))) -->
 1343    { statistics(errors, Errors),
 1344      statistics(warnings, Warnings)
 1345    },
 1346    [ 'Halting with status ~w due to ~D errors and ~D warnings'-
 1347      [Status, Errors, Warnings] ].
 1348
 1349prolog_message(query(QueryResult)) -->
 1350    query_result(QueryResult).
 1351
 1352query_result(no) -->            % failure
 1353    [ ansi(truth(false), 'false.', []) ],
 1354    extra_line.
 1355query_result(yes(true, [])) -->      % prompt_alternatives_on: groundness
 1356    !,
 1357    [ ansi(truth(true), 'true.', []) ],
 1358    extra_line.
 1359query_result(yes(Delays, Residuals)) -->
 1360    result([], Delays, Residuals),
 1361    extra_line.
 1362query_result(done) -->          % user typed <CR>
 1363    extra_line.
 1364query_result(yes(Bindings, Delays, Residuals)) -->
 1365    result(Bindings, Delays, Residuals),
 1366    prompt(yes, Bindings, Delays, Residuals).
 1367query_result(more(Bindings, Delays, Residuals)) -->
 1368    result(Bindings, Delays, Residuals),
 1369    prompt(more, Bindings, Delays, Residuals).
 1370:- if(current_prolog_flag(emscripten, true)). 1371query_result(help) -->
 1372    [ ansi(bold, '  Possible actions:', []), nl,
 1373      '  ; (n,r,space): redo              | t:       trace&redo'-[], nl,
 1374      '  *:             show choicepoint  | . (c,a): stop'-[], nl,
 1375      '  w:             write             | p:       print'-[], nl,
 1376      '  +:             max_depth*5       | -:       max_depth//5'-[], nl,
 1377      '  h (?):         help'-[],
 1378      nl, nl
 1379    ].
 1380:- else. 1381query_result(help) -->
 1382    [ ansi(bold, '  Possible actions:', []), nl,
 1383      '  ; (n,r,space,TAB): redo              | t:           trace&redo'-[], nl,
 1384      '  *:                 show choicepoint  | . (c,a,RET): stop'-[], nl,
 1385      '  w:                 write             | p:           print'-[], nl,
 1386      '  +:                 max_depth*5       | -:           max_depth//5'-[], nl,
 1387      '  b:                 break             | h (?):       help'-[],
 1388      nl, nl
 1389    ].
 1390:- endif. 1391query_result(action) -->
 1392    [ 'Action? '-[], flush ].
 1393query_result(confirm) -->
 1394    [ 'Please answer \'y\' or \'n\'? '-[], flush ].
 1395query_result(eof) -->
 1396    [ nl ].
 1397query_result(toplevel_open_line) -->
 1398    [].
 1399
 1400prompt(Answer, [], true, []-[]) -->
 1401    !,
 1402    prompt(Answer, empty).
 1403prompt(Answer, _, _, _) -->
 1404    !,
 1405    prompt(Answer, non_empty).
 1406
 1407prompt(yes, empty) -->
 1408    !,
 1409    [ ansi(truth(true), 'true.', []) ],
 1410    extra_line.
 1411prompt(yes, _) -->
 1412    !,
 1413    [ full_stop ],
 1414    extra_line.
 1415prompt(more, empty) -->
 1416    !,
 1417    [ ansi(truth(true), 'true ', []), flush ].
 1418prompt(more, _) -->
 1419    !,
 1420    [ ' '-[], flush ].
 1421
 1422result(Bindings, Delays, Residuals) -->
 1423    { current_prolog_flag(answer_write_options, Options0),
 1424      Options = [partial(true)|Options0],
 1425      GOptions = [priority(999)|Options0]
 1426    },
 1427    wfs_residual_program(Delays, GOptions),
 1428    bindings(Bindings, [priority(699)|Options]),
 1429    (   {Residuals == []-[]}
 1430    ->  bind_delays_sep(Bindings, Delays),
 1431        delays(Delays, GOptions)
 1432    ;   bind_res_sep(Bindings, Residuals),
 1433        residuals(Residuals, GOptions),
 1434        (   {Delays == true}
 1435        ->  []
 1436        ;   [','-[], nl],
 1437            delays(Delays, GOptions)
 1438        )
 1439    ).
 1440
 1441bindings([], _) -->
 1442    [].
 1443bindings([binding(Names,Skel,Subst)|T], Options) -->
 1444    { '$last'(Names, Name) },
 1445    var_names(Names), value(Name, Skel, Subst, Options),
 1446    (   { T \== [] }
 1447    ->  [ ','-[], nl ],
 1448        bindings(T, Options)
 1449    ;   []
 1450    ).
 1451
 1452var_names([Name]) -->
 1453    !,
 1454    [ '~w = '-[Name] ].
 1455var_names([Name1,Name2|T]) -->
 1456    !,
 1457    [ '~w = ~w, '-[Name1, Name2] ],
 1458    var_names([Name2|T]).
 1459
 1460
 1461value(Name, Skel, Subst, Options) -->
 1462    (   { var(Skel), Subst = [Skel=S] }
 1463    ->  { Skel = '$VAR'(Name) },
 1464        [ '~W'-[S, Options] ]
 1465    ;   [ '~W'-[Skel, Options] ],
 1466        substitution(Subst, Options)
 1467    ).
 1468
 1469substitution([], _) --> !.
 1470substitution([N=V|T], Options) -->
 1471    [ ', ', ansi(comment, '% where', []), nl,
 1472      '    ~w = ~W'-[N,V,Options] ],
 1473    substitutions(T, Options).
 1474
 1475substitutions([], _) --> [].
 1476substitutions([N=V|T], Options) -->
 1477    [ ','-[], nl, '    ~w = ~W'-[N,V,Options] ],
 1478    substitutions(T, Options).
 1479
 1480
 1481residuals(Normal-Hidden, Options) -->
 1482    residuals1(Normal, Options),
 1483    bind_res_sep(Normal, Hidden),
 1484    (   {Hidden == []}
 1485    ->  []
 1486    ;   [ansi(comment, '% with pending residual goals', []), nl]
 1487    ),
 1488    residuals1(Hidden, Options).
 1489
 1490residuals1([], _) -->
 1491    [].
 1492residuals1([G|Gs], Options) -->
 1493    (   { Gs \== [] }
 1494    ->  [ '~W,'-[G, Options], nl ],
 1495        residuals1(Gs, Options)
 1496    ;   [ '~W'-[G, Options] ]
 1497    ).
 1498
 1499wfs_residual_program(true, _Options) -->
 1500    !.
 1501wfs_residual_program(Goal, _Options) -->
 1502    { current_prolog_flag(toplevel_list_wfs_residual_program, true),
 1503      '$current_typein_module'(TypeIn),
 1504      (   current_predicate(delays_residual_program/2)
 1505      ->  true
 1506      ;   use_module(library(wfs), [delays_residual_program/2])
 1507      ),
 1508      delays_residual_program(TypeIn:Goal, TypeIn:Program),
 1509      Program \== []
 1510    },
 1511    !,
 1512    [ ansi(comment, '% WFS residual program', []), nl ],
 1513    [ ansi(wfs(residual_program), '~@', ['$messages':list_clauses(Program)]) ].
 1514wfs_residual_program(_, _) --> [].
 1515
 1516delays(true, _Options) -->
 1517    !.
 1518delays(Goal, Options) -->
 1519    { current_prolog_flag(toplevel_list_wfs_residual_program, true)
 1520    },
 1521    !,
 1522    [ ansi(truth(undefined), '~W', [Goal, Options]) ].
 1523delays(_, _Options) -->
 1524    [ ansi(truth(undefined), undefined, []) ].
 1525
 1526:- public list_clauses/1. 1527
 1528list_clauses([]).
 1529list_clauses([H|T]) :-
 1530    (   system_undefined(H)
 1531    ->  true
 1532    ;   portray_clause(user_output, H, [indent(4)])
 1533    ),
 1534    list_clauses(T).
 1535
 1536system_undefined((undefined :- tnot(undefined))).
 1537system_undefined((answer_count_restraint :- tnot(answer_count_restraint))).
 1538system_undefined((radial_restraint :- tnot(radial_restraint))).
 1539
 1540bind_res_sep(_, []) --> !.
 1541bind_res_sep(_, []-[]) --> !.
 1542bind_res_sep([], _) --> !.
 1543bind_res_sep(_, _) --> [','-[], nl].
 1544
 1545bind_delays_sep([], _) --> !.
 1546bind_delays_sep(_, true) --> !.
 1547bind_delays_sep(_, _) --> [','-[], nl].
 1548
 1549extra_line -->
 1550    { current_prolog_flag(toplevel_extra_white_line, true) },
 1551    !,
 1552    ['~N'-[]].
 1553extra_line -->
 1554    [].
 1555
 1556prolog_message(if_tty(Message)) -->
 1557    (   {current_prolog_flag(tty_control, true)}
 1558    ->  [ at_same_line ], list(Message)
 1559    ;   []
 1560    ).
 1561prolog_message(halt(Reason)) -->
 1562    [ '~w: halt'-[Reason] ].
 1563prolog_message(no_action(Char)) -->
 1564    [ 'Unknown action: ~c (h for help)'-[Char], nl ].
 1565
 1566prolog_message(history(help(Show, Help))) -->
 1567    [ 'History Commands:', nl,
 1568      '    !!.              Repeat last query', nl,
 1569      '    !nr.             Repeat query numbered <nr>', nl,
 1570      '    !str.            Repeat last query starting with <str>', nl,
 1571      '    !?str.           Repeat last query holding <str>', nl,
 1572      '    ^old^new.        Substitute <old> into <new> of last query', nl,
 1573      '    !nr^old^new.     Substitute in query numbered <nr>', nl,
 1574      '    !str^old^new.    Substitute in query starting with <str>', nl,
 1575      '    !?str^old^new.   Substitute in query holding <str>', nl,
 1576      '    ~w.~21|Show history list'-[Show], nl,
 1577      '    ~w.~21|Show this list'-[Help], nl, nl
 1578    ].
 1579prolog_message(history(no_event)) -->
 1580    [ '! No such event' ].
 1581prolog_message(history(bad_substitution)) -->
 1582    [ '! Bad substitution' ].
 1583prolog_message(history(expanded(Event))) -->
 1584    [ '~w.'-[Event] ].
 1585prolog_message(history(history(Events))) -->
 1586    history_events(Events).
 1587prolog_message(history(no_history)) -->
 1588    [ '! event history not supported in this version' ].
 1589
 1590history_events([]) -->
 1591    [].
 1592history_events([Nr-Event|T]) -->
 1593    [ ansi(comment, '%', []),
 1594      ansi(bold, '~t~w ~6|', [Nr]),
 1595      ansi(code, '~s', [Event]),
 1596      nl
 1597    ],
 1598    history_events(T).