yap 6.2.2-6+b2 / usr / share / Yap / pl / messages.yap

/*************************************************************************
*									 *
*	 YAP Prolog 							 *
*									 *
*	Yap Prolog was developed at NCCUP - Universidade do Porto	 *
*									 *
* Copyright L.Damas, V.S.Costa and Universidade do Porto 1985-1997	 *
*									 *
**************************************************************************
*									 *
* File:		utilities for displaying messages in YAP.		 *
* comments:	error messages for YAP					 *
*									 *
* Last rev:     $Date: 2008-07-16 10:58:59 $,$Author: vsc $						 *
*									 *
*									 *
*************************************************************************/

:- module('$messages',
	  [system_message/4,
	   prefix/6,
	   prefix/5,
	   file_location/3]).

file_location(Prefix) -->
	{
	 prolog_load_context(file, FileName)
	},
	{ '$start_line'(LN) },
	file_position(FileName,LN,Prefix),
	[ nl ].

file_position(user_input,LN,MsgCodes) -->
	[ '~a (user_input:~d).' - [MsgCodes,LN] ].
file_position(FileName,LN,MsgCodes) -->
	[ '~a (~a:~d).' - [MsgCodes,FileName,LN] ].

generate_message(halt) --> !,
	['YAP execution halted'].
generate_message('$abort') --> !,
	['YAP execution aborted'].
generate_message(abort(user)) --> !,
	['YAP execution aborted'].
generate_message(loading(_,user)) --> !.
generate_message(loading(What,AbsoluteFileName)) --> !,
	[ '~a ~a...' - [What, AbsoluteFileName] ].
generate_message(loaded(_,user,_,_,_)) --> !.
generate_message(loaded(included,AbsoluteFileName,Mod,Time,Space)) --> !,
	[ '~a included in module ~a, ~d msec ~d bytes' - [AbsoluteFileName,Mod,Time,Space] ].
generate_message(loaded(What,AbsoluteFileName,Mod,Time,Space)) --> !,
	[ '~a ~a in module ~a, ~d msec ~d bytes' - [What, AbsoluteFileName,Mod,Time,Space] ].
generate_message(prompt(BreakLevel,TraceDebug)) --> !,
	( { BreakLevel =:= 0 } ->
	    (
	     { var(TraceDebug) } ->
	     []
	    ;
	     [ '~a' - [TraceDebug] ]
	    )
	;
	    (
	     { var(TraceDebug) } ->
	     [ '~d' - [BreakLevel] ]
	    ;
	     [ '~d ~a' - [BreakLevel, TraceDebug] ]
	    )
	).
generate_message(debug) --> !,
	[ debug ].
generate_message(trace) --> !,
	[ trace ].
generate_message(M) -->
	system_message(M),
	stack_dump(M).

stack_dump(error(_,_)) -->
	{ fail }, 
	{ recorded(sp_info,local_sp(P,CP,Envs,CPs),_) },
	{ Envs = [_|_] ; CPs = [_|_] }, !,
	[nl],
	'$hacks':display_stack_info(CPs, Envs, 20, CP).
stack_dump(_) --> [].

prolog_message(X,Y,Z) :-
	system_message(X,Y,Z).	      

%message(loaded(Past,AbsoluteFileName,user,Msec,Bytes), Prefix, Suffix) :- !,
system_message(query(_QueryResult,_)) --> [].
system_message(format(Msg, Args)) -->
	[Msg - Args].
system_message(ancestors([])) -->
	[ 'There are no ancestors.' ].
system_message(breakp(bp(debugger,_,_,M:F/N,_),add,already)) -->
	[ 'There is already a spy point on ~w:~w/~w.' - [M,F,N]].
system_message(breakp(bp(debugger,_,_,M:F/N,_),add,ok)) -->
	[ 'Spy point set on ~w:~w/~w.' - [M,F,N] ].
system_message(breakp(bp(debugger,_,_,M:F/N,_),remove,last)) -->
	[ 'Spy point on ~w:~w/~w removed.' - [M,F,N] ].
system_message(breakp(no,breakpoint_for,M:F/N)) -->
	[ 'There is no spy point on ~w:~w/~w.' - [M,F,N]].
system_message(breakpoints([])) -->
	[ 'There are no spy-points set.' ].
system_message(breakpoints(L)) -->
	[ 'Spy-points set on:' ],
	list_of_preds(L).
system_message(clauses_not_together(P)) -->
	[ 'Discontiguous definition of ~q.' - [P] ].
system_message(debug(debug)) -->
	[ 'Debug mode on.' ].
system_message(debug(off)) -->
	[ 'Debug mode off.' ].
system_message(debug(trace)) -->
	[ 'Trace mode on.' ].
system_message(declaration(Args,Action)) -->
	[ 'declaration ~w ~w.' - [Args,Action] ].
system_message(defined_elsewhere(P,F)) -->
	[  'predicate ~q previously defined in file ~w' - [P,F] ].
system_message(import(Pred,To,From,private)) -->
	[ 'Importing private predicate ~w:~w to ~w.' - [From,Pred,To] ].
system_message(leash([])) -->
	[ 'No leashing.' ].
system_message(leash([A|B])) -->
	[ 'Leashing set to ~w.' - [[A|B]] ].
system_message(no) -->
	[ 'no'  ].
system_message(no_match(P)) -->
	[ 'No matching predicate for ~w.' - [P] ].
system_message(leash([A|B])) -->
	[ 'Leashing set to ~w.' - [[A|B]] ].
system_message(existence_error(prolog_flag,F)) -->
	[ 'Prolog Flag ~w: new Prolog flags must be created using create_prolog_flag/3.' - [F] ].
system_message(singletons([SV],P)) -->
	[ 'Singleton variable ~s in ~q.' - [SV,P] ].
system_message(singletons(SVs,P)) -->
	[  'Singleton variables ~s in ~q.' - [SVsL, P] ],
	{ svs(SVs,SVsL,[]) }.
system_message(trace_command(-1)) -->
	[ 'EOF is not a valid debugger command.'  ].
system_message(trace_command(C)) -->
	[ '~c is not a valid debugger command.' - [C] ].
system_message(trace_help) -->
	[ '   Please enter a valid debugger command (h for help).'  ].
system_message(version(Version)) -->
	[ '~a' - [Version] ].
system_message(myddas_version(Version)) -->
	[ 'MYDDAS version ~a' - [Version] ].
system_message(yes) -->
	[  'yes'  ].
system_message(error,error(Msg,Info)) -->
	( { var(Msg) } ; { var(Info)} ), !,
	['bad error ~w' - [error(Msg,Info)]].
system_message(error(consistency_error(Who),Where)) -->
	[ 'CONSISTENCY ERROR (arguments not compatible with format)- ~w ~w' - [Who,Where] ].
system_message(error(context_error(Goal,Who),Where)) -->
	[ 'CONTEXT ERROR- ~w: ~w appeared in ~w' - [Goal,Who,Where] ].
system_message(error(domain_error(DomainType,Opt), Where)) -->
	[ 'DOMAIN ERROR- ~w: ' - Where],
	domain_error(DomainType, Opt).
system_message(error(existence_error(prolog_flag,P), Where)) --> !,
	[ 'EXISTENCE ERROR- ~w: prolog flag ~w is undefined' - [Where,P] ].
system_message(error(existence_error(procedure,P), context(Call,Parent))) --> !,
	[ 'EXISTENCE ERROR- procedure ~w is undefined, called from context  ~w~n                 Goal was ~w' - [P,Parent,Call] ].
system_message(error(existence_error(stream,Stream), Where)) -->
	[ 'EXISTENCE ERROR- ~w: ~w not an open stream' - [Where,Stream] ].
system_message(error(existence_error(key,Key), Where)) -->
	[ 'EXISTENCE ERROR- ~w: ~w not an existing key' - [Where,Key] ].
system_message(error(existence_error(thread,Thread), Where)) -->
	[ 'EXISTENCE ERROR- ~w: ~w not a running thread' - [Where,Thread] ].
system_message(error(existence_error(variable,Var), Where)) -->
	[ 'EXISTENCE ERROR- ~w: variable ~w does not exist' - [Where,Var] ].
system_message(error(existence_error(Name,F), W)) -->
	{ object_name(Name, ObjName) },
	[ 'EXISTENCE ERROR- ~w could not open ~a ~w' - [W,ObjName,F] ].
system_message(error(evaluation_error(int_overflow), Where)) -->
	[ 'INTEGER OVERFLOW ERROR- ~w' - [Where] ].
system_message(error(evaluation_error(float_overflow), Where)) -->
	[ 'FLOATING POINT OVERFLOW ERROR- ~w' - [Where] ].
system_message(error(evaluation_error(undefined), Where)) -->
	[ 'UNDEFINED ARITHMETIC RESULT ERROR- ~w' - [Where] ].
system_message(error(evaluation_error(underflow), Where)) -->
	[ 'UNDERFLOW ERROR- ~w' - [Where] ].
system_message(error(evaluation_error(float_underflow), Where)) -->
	[ 'FLOATING POINT UNDERFLOW ERROR- ~w' - [Where] ].
system_message(error(evaluation_error(zero_divisor), Where)) -->
	[ 'ZERO DIVISOR ERROR- ~w' - [Where] ].
system_message(error(instantiation_error, Where)) -->
	[ 'INSTANTIATION ERROR- ~w: expected bound value' - [Where] ].
system_message(error(not_implemented(Type, What), Where)) -->
	[ '~w not implemented- ~w' - [Type, What] ].
system_message(error(operating_system_error, Where)) -->
	[ 'OPERATING SYSTEM ERROR- ~w' - [Where] ].
system_message(error(out_of_heap_error, Where)) -->
	[ 'OUT OF DATABASE SPACE ERROR- ~w' - [Where] ].
system_message(error(out_of_stack_error, Where)) -->
	[ 'OUT OF STACK SPACE ERROR- ~w' - [Where] ].
system_message(error(out_of_trail_error, Where)) -->
	[ 'OUT OF TRAIL SPACE ERROR- ~w' - [Where] ].
system_message(error(out_of_attvars_error, Where)) -->
	[ 'OUT OF STACK SPACE ERROR- ~w' - [Where] ].
system_message(error(out_of_auxspace_error, Where)) -->
	[ 'OUT OF AUXILIARY STACK SPACE ERROR- ~w' - [Where] ].
system_message(error(permission_error(access,private_procedure,P), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot see clauses for ~w' - [Where,P] ].
system_message(error(permission_error(access,static_procedure,P), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot access static procedure ~w' - [Where,P] ].
system_message(error(permission_error(alias,new,P), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot create alias ~w' - [Where,P] ].
system_message(error(permission_error(create,Name,P), Where)) -->
	{ object_name(Name, ObjName) },
	[ 'PERMISSION ERROR- ~w: cannot create ~a ~w' - [Where,ObjName,P] ].
system_message(error(permission_error(input,binary_stream,Stream), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot read from binary stream ~w' - [Where,Stream] ].
system_message(error(permission_error(input,closed_stream,Stream), Where)) -->
	[ 'PERMISSION ERROR- ~w: trying to read from closed stream ~w' - [Where,Stream] ].
system_message(error(permission_error(input,past_end_of_stream,Stream), Where)) -->
	[ 'PERMISSION ERROR- ~w: past end of stream ~w' - [Where,Stream] ].
system_message(error(permission_error(input,stream,Stream), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot read from ~w' - [Where,Stream] ].
system_message(error(permission_error(input,text_stream,Stream), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot read from text stream ~w' - [Where,Stream] ].
system_message(error(permission_error(modify,dynamic_procedure,_), Where)) -->
	[ 'PERMISSION ERROR- ~w: modifying a dynamic procedure' - [Where] ].
system_message(error(permission_error(modify,flag,W), _)) -->
	[ 'PERMISSION ERROR- cannot modify flag ~w' - [W] ].
system_message(error(permission_error(modify,operator,W), Q)) -->
	[ 'PERMISSION ERROR- ~w: cannot modify operator ~q' - [Q,W] ].
system_message(error(permission_error(modify,dynamic_procedure,F), Where)) -->
	[ 'PERMISSION ERROR- ~w: modifying dynamic procedure ~w' - [Where,F] ].
system_message(error(permission_error(modify,static_procedure,F), Where)) -->
	[ 'PERMISSION ERROR- ~w: modifying static procedure ~w' - [Where,F] ].
system_message(error(permission_error(modify,static_procedure_in_use,_), Where)) -->
	[ 'PERMISSION ERROR- ~w: modifying a static procedure in use' - [Where] ].
system_message(error(permission_error(modify,table,P), _)) -->
	[ 'PERMISSION ERROR- cannot table procedure ~w' - [P] ].
system_message(error(permission_error(module,redefined,Mod), Who)) -->
	[ 'PERMISSION ERROR ~w- redefining module ~a in a different file' - [Who,Mod] ].
system_message(error(permission_error(open,source_sink,Stream), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot open file ~w' - [Where,Stream] ].
system_message(error(permission_error(output,binary_stream,Stream), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot write to binary stream ~w' - [Where,Stream] ].
system_message(error(permission_error(output,stream,Stream), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot write to ~w' - [Where,Stream] ].
system_message(error(permission_error(output,text_stream,Stream), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot write to text stream ~w' - [Where,Stream] ].
system_message(error(permission_error(resize,array,P), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot resize array ~w' - [Where,P] ].
system_message(error(permission_error(unlock,mutex,P), Where)) -->
	[ 'PERMISSION ERROR- ~w: cannot unlock mutex ~w' - [Where,P] ].
system_message(error(representation_error(character), Where)) -->
	[ 'REPRESENTATION ERROR- ~w: expected character' - [Where] ].
system_message(error(representation_error(character_code), Where)) -->
	[ 'REPRESENTATION ERROR- ~w: expected character code' - [Where] ].
system_message(error(representation_error(max_arity), Where)) -->
	[ 'REPRESENTATION ERROR- ~w: number too big' - [Where] ].
system_message(error(representation_error(variable), Where)) -->
	[ 'REPRESENTATION ERROR- ~w: should be a variable' - [Where] ].
system_message(error(resource_error(code_space), Where)) -->
	[ 'RESOURCE ERROR- not enough code space' - [Where] ].
system_message(error(resource_error(huge_int), Where)) -->
	[ 'RESOURCE ERROR- too large an integer in absolute value' - [Where] ].
system_message(error(resource_error(memory), Where)) -->
	[ 'RESOURCE ERROR- not enough virtual memory' - [Where] ].
system_message(error(resource_error(stack), Where)) -->
	[ 'RESOURCE ERROR- not enough stack' - [Where] ].
system_message(error(resource_error(streams), Where)) -->
	[ 'RESOURCE ERROR- could not find a free stream' - [Where] ].
system_message(error(resource_error(threads), Where)) -->
	[ 'RESOURCE ERROR- too many open threads' - [Where] ].
system_message(error(resource_error(trail), Where)) -->
	[ 'RESOURCE ERROR- not enough trail space' - [Where] ].
system_message(error(signal(SIG,_), _)) -->
	[ 'UNEXPECTED SIGNAL: ~a' - [SIG] ].
system_message(error(syntax_error(syntax_error(G,0,Msg,[],0,0,File)), _)) -->
	[ 'SYNTAX ERROR at "~a", goal ~q: ~a' - [File,G,Msg] ].
system_message(error(syntax_error(syntax_error(read(Term),_,_,Term,Pos,Start,File)), Where)) -->
	['~w' - [Where]],
	syntax_error_line(File, Start, Pos),
	syntax_error_term(10, Pos, Term),
	[ '.' ].
system_message(error(system_error, Where)) -->
	[ 'SYSTEM ERROR- ~w' - [Where] ].
system_message(error(internal_compiler_error, Where)) -->
	[ 'INTERNAL COMPILER ERROR- ~w' - [Where] ].
system_message(error(system_error(Message), Where)) -->
	[ 'SYSTEM ERROR- ~w at ~w]' - [Message,Where] ].
system_message(error(timeout_error(T,Obj), _Where)) -->
	[ 'TIMEOUT ERROR- operation ~w on object ~w' - [T,Obj] ].
system_message(error(type_error(T,_,Err,M), _Where)) -->
	[ 'TYPE ERROR- ~w: expected ~w, got ~w' - [T,Err,M] ].
system_message(error(type_error(TE,W), Where)) -->
	{ object_name(TE, M) }, !,
	[ 'TYPE ERROR- ~w: expected ~a, got ~w' - [Where,M,W] ].
system_message(error(type_error(TE,W), Where)) -->
	[ 'TYPE ERROR- ~w: expected ~q, got ~w' - [Where,TE,W] ].
system_message(error(unknown, Where)) -->
	[ 'EXISTENCE ERROR- procedure ~w undefined' - [Where] ].
system_message(error(unhandled_exception,Throw)) -->
	[ 'UNHANDLED EXCEPTION - message ~w unknown' - [Throw] ].
system_message(error(uninstantiation_error(TE), Where)) -->
	[ 'UNINSTANTIATION ERROR - expected unbound term, got ~q' - [TE] ].
system_message(Messg) -->
	[ '~q' - Messg ].


domain_error(array_overflow, Opt) --> !,
	[ 'invalid static index ~w for array' - Opt ].
domain_error(array_type, Opt) --> !,
	[ 'invalid static array type ~w' - Opt ].
domain_error(builtin_procedure, _) --> !,
	[ 'non-iso built-in procedure'  ].
domain_error(character_code_list, Opt) --> !,
	[ 'invalid list of codes ~w' - [Opt] ].
domain_error(close_option, Opt) --> !,
	[ 'invalid close option ~w' - [Opt] ].
domain_error(delete_file_option, Opt) --> !,
	[ 'invalid list of options ~w' - [Opt] ].
domain_error(encoding, Opt) --> !,
	[ 'invalid encoding ~w' - [Opt] ].
domain_error(flag_value, Opt) --> !,
	[ 'invalid value ~w for flag ~w' - [Opt] ].
domain_error(io_mode, Opt) --> !,
	[ 'invalid io mode ~w' - [Opt] ].
domain_error(mutable, Opt) --> !,
	[ 'invalid id mutable ~w' - [Opt] ].
domain_error(module_decl_options, Opt) --> !,
	[ 'expect module declaration options, found ~w' - [Opt] ].
domain_error(non_empty_list, Opt) --> !,
	[ 'found empty list' - [Opt] ].
domain_error(not_less_than_zero, Opt) --> !,
	[ 'number ~w less than zero' - [Opt] ].
domain_error(not_newline, Opt) --> !,
	[ 'number ~w not newline' - [Opt] ].
domain_error(not_zero, Opt) --> !,
	[ '~w is not allowed in the domain' - [Opt] ].
domain_error(operator_priority, Opt) --> !,
	[ '~w invalid operator priority' - [Opt] ].
domain_error(operator_specifier, Opt) --> !,
	[ 'invalid operator specifier ~w' - [Opt] ].
domain_error(out_of_range, Opt) --> !,
	[ 'expression ~w is out of range' - [Opt] ].
domain_error(predicate_spec, Opt) --> !,
	[ '~w invalid predicate specifier' - [Opt] ].
domain_error(radix, Opt) --> !,
	[ 'invalid radix ~w' - [Opt] ].
vdomain_error(read_option, Opt) --> !,
	[ '~w invalid option to read_term' - [Opt] ].
domain_error(semantics_indicatior, Opt) --> !,
	[ '~w expected predicate indicator, got ~w' - [Opt] ].
domain_error(shift_count_overflow, Opt) --> !,
	[ 'shift count overflow in ~w' - [Opt] ].
domain_error(source_sink, Opt) --> !,
	[ '~w is not a source sink term' - [Opt] ].
domain_error(stream, Opt) --> !,
	[ '~w is not a stream' - [Opt] ].
domain_error(stream_or_alias, Opt) --> !,
	[ '~w is not a stream (or alias)' - [Opt] ].
domain_error(stream_encoding, Opt) --> !,
	[ '~w is not a supported stream encoding' - [Opt] ].
domain_error(stream_position, Opt) --> !,
	[ '~w is not a stream position' - [Opt] ].
domain_error(stream_property, Opt) --> !,
	[ '~w is not a stream property' - [Opt] ].
domain_error(syntax_error_handler, Opt) --> !,
	[ '~w is not a syntax error handler' - [Opt] ].
domain_error(table, Opt) --> !,
	[ 'non-tabled procedure ~w' - [Opt] ].
domain_error(thread_create_option, Opt) --> !,
	[ '~w is not a thread_create option' - [Opt] ].
domain_error(time_out_spec, Opt) --> !,
	[ '~w is not valid specificatin for time_out' - [Opt] ].
domain_error(unimplemented_option, Opt) --> !,
	[ '~w is not yet implemented' - [Opt] ].
domain_error(write_option, Opt) --> !,
	[ '~w invalid write option' - [Opt] ].
domain_error(Domain, Opt) -->
	[ '~w not a valid element for ~w' - [Opt,Domain] ].


object_name(array, array).
object_name(atom, atom).
object_name(atomic, atomic).
object_name(byte, byte).
object_name(callable, 'callable goal').
object_name(char, char).
object_name(character_code, 'character code').
object_name(compound, 'compound term').
object_name(db_reference, 'data base reference').
object_name(evaluable, 'evaluable term').
object_name(file, file).
object_name(float, float).
object_name(in_byte, byte).
object_name(in_character, character).
object_name(integer, integer).
object_name(key, 'database key').
object_name(leash_mode, 'leash mode').
object_name(library, library).
object_name(list, list).
object_name(message_queue, 'message queue').
object_name(mutex, mutex).
object_name(number, number).
object_name(operator, operator).
object_name(pointer, pointer).
object_name(predicate_indicator, 'predicate indicator').
object_name(source_sink, file).
object_name(unsigned_byte, 'unsigned byte').
object_name(unsigned_char, 'unsigned char').
object_name(variable, 'unbound variable').

svs([H]) --> !, H.
svs([H|L]) -->
	H,
	", ",
	svs(L).

list_of_preds([]) --> [].
list_of_preds([P|L]) -->
	['~q' - [P]],
	list_of_preds(L).


syntax_error_line(File, Position,_) -->
	[' at ~a, near line ~d:~n' - [File,Position]].

syntax_error_term(0,J,L) -->
	['~n' ],
	syntax_error_term(10,J,L).
syntax_error_term(_,0,L) --> !,
	[ '~n<==== HERE ====>~n' ],
	syntax_error_term(10,-1,L).
syntax_error_term(_,_,[]) --> !.
syntax_error_term(I,J,[T-_P|R]) -->
	syntax_error_token(T),
	{
	 I1 is I-1,
	 J1 is J-1
	},
	syntax_error_term(I1,J1,R).

syntax_error_token(atom(A)) --> !,
	[ ' ~a' - [A] ].
syntax_error_token(number(N)) --> !,
	[ ' ~w' - [N] ].
syntax_error_token(var(_,S,_))  --> !,
	[ ' ~s'  - [S] ].
syntax_error_token(string(S)) --> !,
	[ ' ""~s"' - [S] ].
syntax_error_token('(') --> !,
	[ '('  ].
syntax_error_token(')') --> !,
	[ ' )'  ].
syntax_error_token(',') --> !,
	[ ' ,' ].
syntax_error_token(A) --> !,
	[ ' ~a' - [A] ].


%	print_message_lines(+Stream, +Prefix, +Lines)
%
%	Quintus/SICStus/SWI compatibility predicate to print message lines
%       using  a prefix.

prolog:print_message_lines(_, _, []) :- !.
prolog:print_message_lines(S, P, [at_same_line|Lines]) :- !,
	print_message_line(S, Lines, Rest),
	prolog:print_message_lines(S, P, Rest).
prolog:print_message_lines(S, P-Opts, Lines) :- !,
	atom_concat('~N', P, Prefix),
	format(S, Prefix, Opts),
	print_message_line(S, Lines, Rest),
	prolog:print_message_lines(S, P-Opts, Rest).
prolog:print_message_lines(S, P, Lines) :-
	atom_concat('~N', P, Prefix),
	format(S, Prefix, []),
	print_message_line(S, Lines, Rest),
	prolog:print_message_lines(S, P, Rest).

print_message_line(S, [flush], []) :- !,
	flush_output(S).
print_message_line(S, [], []) :- !,
	nl(S).
print_message_line(S, [nl|T], T) :- !,
	nl(S).
print_message_line(S, [Fmt-Args|T0], T) :- !,
	format(S, Fmt, Args),
	print_message_line(S, T0, T).
print_message_line(S, [Fmt|T0], T) :-
	format(S, Fmt, []),
	print_message_line(S, T0, T).

prefix(error,   '     ', user_error, 'ERROR!! ').
prefix(warning, '% ', user_error, 'Warning: ').

prefix(help,	      '',          user_error) --> [].
prefix(query,	      '',          user_error) --> [].
prefix(debug,	      '',          user_output) --> [].
prefix(warning,	      '% ',      user_error) -->
	{ thread_self(Id) },
	(   { Id == main }
	->  [ 'Warning: ', nl ]
	;   ['Warning: [Thread ~d ]' - Id, nl ]
	).
prefix(error,	      '     ',   user_error) -->
	{ recorded(sp_info,local_sp(P,_,_,_),_) },
	{ thread_self(Id) },
	(   { Id == main }
	->  [ 'ERROR at ' ]
	;   [ 'ERROR [Thread ~d ] at ' - Id ]
	),
	'$hacks':display_pc(P),
	!,
	[' !!', nl].
prefix(error,	      '     ',   user_error) -->
	{ thread_self(Id) },
	(   { Id == main }
	->  [ 'ERROR!!', nl ]
	;   [ 'ERROR!! [Thread ~d ]' - Id, nl ]
	).
prefix(banner,	      '',	   user_error) --> [].
prefix(informational, '~*|% '-[LC],     user_error) -->
	{ '$show_consult_level'(LC) }.