Logtalk 2.28.2 files.

git-svn-id: https://yap.svn.sf.net/svnroot/yap/trunk@1712 b08c6af1-5177-4d33-ba66-4b1c6b8b522a
2006-11-07 18:11:49 +00:00
parent 36a326908c
commit 2d7ccc1278
168 changed files with 3143 additions and 1018 deletions
--- a/Logtalk/examples/NOTES.txt
+++ b/Logtalk/examples/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
@@ -27,7 +27,9 @@ code or from known Prolog text books and are copyrighted by the respective
 authors.

 These are programming examples, meaning that you should study the source 
-files to fully understand them.
+files to fully understand them. However, note that some examples purpose 
+is to illustrate general principles rather than being adequate, efficient 
+solutions for deployment code.

 All examples are formatted using four spaces tabs.

@@ -109,10 +111,11 @@ lpa
 	examples adopted from the LPA Prolog++ system

 metapredicates
-	example of using metapredicates in Logtalk objects
+	example of using meta-predicates in Logtalk objects

 metainterpreters
-	some examples of simple metainterpreters
+	some examples of simple meta-interpreters defined as categories which 
+	may be imported by "database" objects

 mi
 	multi-inheritance examples
@@ -177,5 +180,8 @@ symdiff
 	example of using parametric objects to implement symbolic expression 
 	differentiation and simplification

+threads
+	several simple examples of multi-threading programming
+
 viewpoints
 	example on how to implement property and value sharing with prototypes
--- a/Logtalk/examples/aliases/NOTES.txt
+++ b/Logtalk/examples/aliases/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/aliases/SCRIPT.txt
+++ b/Logtalk/examples/aliases/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/assignvars/NOTES.txt
+++ b/Logtalk/examples/assignvars/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/assignvars/SCRIPT.txt
+++ b/Logtalk/examples/assignvars/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/benchmarks/NOTES.txt
+++ b/Logtalk/examples/benchmarks/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/benchmarks/SCRIPT.txt
+++ b/Logtalk/examples/benchmarks/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/birds/NOTES.txt
+++ b/Logtalk/examples/birds/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/birds/SCRIPT.txt
+++ b/Logtalk/examples/birds/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/bricks/NOTES.txt
+++ b/Logtalk/examples/bricks/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/bricks/SCRIPT.txt
+++ b/Logtalk/examples/bricks/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/classvars/NOTES.txt
+++ b/Logtalk/examples/classvars/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/classvars/SCRIPT.txt
+++ b/Logtalk/examples/classvars/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/dcgs/NOTES.txt
+++ b/Logtalk/examples/dcgs/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/dcgs/SCRIPT.txt
+++ b/Logtalk/examples/dcgs/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
@@ -20,6 +20,13 @@ Result = -9
 yes


+% Recognize MAC addresses:
+
+| ?- macaddr::valid("00:1e:4a:ef:72:8b").
+
+yes
+
+
 % solve a cellphone keypad encoded enigma:

 | ?- enigma::solve("4 96853 5683 86 4283 346637 9484 968 8664448", Message).
--- a/Logtalk/examples/dcgs/macaddr.lgt
+++ b/Logtalk/examples/dcgs/macaddr.lgt
@@ -0,0 +1,17 @@
+
+:- object(macaddr).
+
+	:- public(valid/1).
+
+	valid(Address) :-
+		phrase(mac, Address).
+
+	mac --> digits, ":", digits, ":", digits, ":", digits, ":", digits, ":", digits.
+
+	digits --> digit, digit.
+
+	digit --> [C], {0'0 =< C, C =< 0'9}.
+	digit --> [C], {0'a =< C, C =< 0'f}.
+	digit --> [C], {0'A =< C, C =< 0'F}.
+
+:- end_object.
--- a/Logtalk/examples/diamonds/NOTES.txt
+++ b/Logtalk/examples/diamonds/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/diamonds/SCRIPT.txt
+++ b/Logtalk/examples/diamonds/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/dynpred/NOTES.txt
+++ b/Logtalk/examples/dynpred/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/dynpred/SCRIPT.txt
+++ b/Logtalk/examples/dynpred/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/encodings/NOTES.txt
+++ b/Logtalk/examples/encodings/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/encodings/SCRIPT.txt
+++ b/Logtalk/examples/encodings/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/engines/NOTES.txt
+++ b/Logtalk/examples/engines/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/engines/SCRIPT.txt
+++ b/Logtalk/examples/engines/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/errors/NOTES.txt
+++ b/Logtalk/examples/errors/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/errors/SCRIPT.txt
+++ b/Logtalk/examples/errors/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/expansion/NOTES.txt
+++ b/Logtalk/examples/expansion/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/expansion/SCRIPT.txt
+++ b/Logtalk/examples/expansion/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/hello_world/NOTES.txt
+++ b/Logtalk/examples/hello_world/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/hello_world/SCRIPT.txt
+++ b/Logtalk/examples/hello_world/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/hooks/NOTES.txt
+++ b/Logtalk/examples/hooks/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/hooks/SCRIPT.txt
+++ b/Logtalk/examples/hooks/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/inheritance/NOTES.txt
+++ b/Logtalk/examples/inheritance/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/inheritance/SCRIPT.txt
+++ b/Logtalk/examples/inheritance/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/instmethods/NOTES.txt
+++ b/Logtalk/examples/instmethods/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/instmethods/SCRIPT.txt
+++ b/Logtalk/examples/instmethods/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/lo/NOTES.txt
+++ b/Logtalk/examples/lo/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/lo/planner/NOTES.txt
+++ b/Logtalk/examples/lo/planner/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/lo/planner/SCRIPT.txt
+++ b/Logtalk/examples/lo/planner/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/lo/travellers/NOTES.txt
+++ b/Logtalk/examples/lo/travellers/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/lo/travellers/SCRIPT.txt
+++ b/Logtalk/examples/lo/travellers/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/logic/NOTES.txt
+++ b/Logtalk/examples/logic/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/logic/SCRIPT.txt
+++ b/Logtalk/examples/logic/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/lpa/NOTES.txt
+++ b/Logtalk/examples/lpa/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/lpa/faults/NOTES.txt
+++ b/Logtalk/examples/lpa/faults/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/lpa/faults/SCRIPT.txt
+++ b/Logtalk/examples/lpa/faults/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/lpa/timetables/NOTES.txt
+++ b/Logtalk/examples/lpa/timetables/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/lpa/timetables/SCRIPT.txt
+++ b/Logtalk/examples/lpa/timetables/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/metainterpreters/NOTES.txt
+++ b/Logtalk/examples/metainterpreters/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
@@ -9,7 +9,7 @@ Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 To load this example and for sample queries, please see the SCRIPT file.

 This example contains simple meta-interpreters for pure Prolog encapsulated 
-in Logtalk objects:
+in Logtalk categories:

 	solver
 		simple meta-interpreter for pure Prolog
@@ -21,3 +21,6 @@ in Logtalk objects:
 	tracer
 		simple meta-interpreter for pure Prolog that traces proof 
 		construction
+
+To use a meta-interpreter with an object, simply import the corresponding 
+category.
--- a/Logtalk/examples/metainterpreters/SCRIPT
+++ b/Logtalk/examples/metainterpreters/SCRIPT
@@ -1,113 +0,0 @@
-=================================================================
-Logtalk - Object oriented extension to Prolog
-Release 2.27.1
-
-Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
-=================================================================
-
-
-% start by loading the example:
-
-| ?- logtalk_load(metainterpreters(loader)).
-...
-
-
-% solver - a simple meta-interpreter for pure Prolog:
-
-| ?- solver::assertz(member_of(H, [H| _])).
-
-H = _G178 
-yes
-
-| ?- solver::assertz((member_of(H, [_| T]) :- member_of(H, T))).
-
-H = _G181
-T = _G179 
-yes
-
-| ?- solver::solve(member_of(2, [1,2,3])).
-
-yes
-
-| ?- solver::solve(member_of(X, [1,2,3])).
-
-X = 1 ;
-X = 2 ;
-X = 3
-yes
-
-
-% proof_tree - a simple meta-interpreter for pure Prolog that 
-% construct a proof tree:
-
-| ?- proof_tree::assertz(member_of(H, [H| _])).
-
-H = _G178 
-yes
-
-| ?- proof_tree::assertz((member_of(H, [_| T]) :- member_of(H, T))).
-
-H = _G181
-T = _G179 
-yes
-
-| ?- proof_tree::solve(member_of(2, [1,2,3]), Tree).
-
-Tree = member_of(2, [1, 2, 3]):- (member_of(2, [2, 3]):-true) 
-yes
-
-
-% tracer - a simple meta-interpreter for tracing goal proofs 
-% using pure Prolog:
-
-
-| ?- tracer::assertz(member_of(H, [H| _])).
-
-H = _G178 
-yes
-
-| ?- tracer::assertz((member_of(H, [_| T]) :- member_of(H, T))).
-
-H = _G181
-T = _G179 
-yes
-
-| ?- tracer::trace(member_of(3, [1,2,3])).
-
-1 call: member_of(3, [1, 2, 3])
-2 call: member_of(3, [2, 3])
-3 call: member_of(3, [3])
-3 exit: member_of(3, [3])
-2 exit: member_of(3, [2, 3])
-1 exit: member_of(3, [1, 2, 3])
-yes
-
-| ?- tracer::trace(member_of(X, [1,2,3])).
-
-1 call: member_of(_G187, [1, 2, 3])
-1 exit: member_of(1, [1, 2, 3])
-
-X = 1 ;
-1 redo: member_of(1, [1, 2, 3])
-2 call: member_of(_G187, [2, 3])
-2 exit: member_of(2, [2, 3])
-1 exit: member_of(2, [1, 2, 3])
-
-X = 2 ;
-1 redo: member_of(2, [1, 2, 3])
-2 redo: member_of(2, [2, 3])
-3 call: member_of(_G187, [3])
-3 exit: member_of(3, [3])
-2 exit: member_of(3, [2, 3])
-1 exit: member_of(3, [1, 2, 3])
-
-X = 3 ;
-1 redo: member_of(3, [1, 2, 3])
-2 redo: member_of(3, [2, 3])
-3 redo: member_of(3, [3])
-4 call: member_of(_G187, [])
-4 fail: member_of(_G187, [])
-3 fail: member_of(_G187, [3])
-2 fail: member_of(_G187, [2, 3])
-1 fail: member_of(_G187, [1, 2, 3])
-no
--- a/Logtalk/examples/metainterpreters/SCRIPT.txt
+++ b/Logtalk/examples/metainterpreters/SCRIPT.txt
@@ -0,0 +1,100 @@
+=================================================================
+Logtalk - Object oriented extension to Prolog
+Release 2.28.2
+
+Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
+=================================================================
+
+
+% start by loading the example:
+
+| ?- logtalk_load(metainterpreters(loader)).
+...
+
+
+% direct call of p/1:
+
+| ?- ?- database::p(X).
+
+X = 1 ;
+X = 2 
+yes
+
+
+% solver - a simple meta-interpreter for pure Prolog:
+
+| ?- database::solve(p(X)).
+
+X = 1 ;
+X = 2 
+yes
+
+| ?- database::proof_tree(p(X), Tree).
+
+X = 1
+Tree = p(1):- (q(1, a):- (s(1):-true), (t(1, a):-true)), (r(a):-true) ;
+X = 2
+Tree = p(2):- (q(2, b):- (s(2):-true), (t(2, b):-true)), (r(b):-true) 
+yes
+
+
+% tracer - a simple meta-interpreter for tracing goal proofs using pure Prolog:
+
+| ?- database::trace(p(X)).
+1 call: p(_G180)
+2 call: q(_G180, _G316)
+3 call: s(_G180)
+3 exit: s(1)
+3 call: t(1, _G316)
+3 exit: t(1, a)
+2 exit: q(1, a)
+2 call: r(a)
+2 exit: r(a)
+1 exit: p(1)
+
+X = 1 ;
+1 redo: p(1)
+2 redo: r(a)
+2 fail: r(a)
+2 redo: q(1, a)
+3 redo: t(1, a)
+3 fail: t(1, _G316)
+3 redo: s(1)
+3 exit: s(2)
+3 call: t(2, _G316)
+3 exit: t(2, b)
+2 exit: q(2, b)
+2 call: r(b)
+2 exit: r(b)
+1 exit: p(2)
+
+X = 2 ;
+1 redo: p(2)
+2 redo: r(b)
+2 fail: r(b)
+2 redo: q(2, b)
+3 redo: t(2, b)
+3 fail: t(2, _G316)
+3 redo: s(2)
+3 exit: s(3)
+3 call: t(3, _G316)
+3 fail: t(3, _G316)
+3 redo: s(3)
+3 fail: s(_G180)
+2 fail: q(_G180, _G316)
+1 fail: p(_G180)
+
+no
+
+
+% another example: expert system rules:
+
+| rules::prove(weather(Wheather)).
+
+Wheather = raining 
+yes
+
+| ?- rules::prove(goto(Where)).
+
+Where = cinema 
+yes
--- a/Logtalk/examples/metainterpreters/database.lgt
+++ b/Logtalk/examples/metainterpreters/database.lgt
@@ -0,0 +1,23 @@
+
+:- object(database,
+	imports(solver, proof_tree, tracer)).
+
+	:- public(p/1).
+	:- private(q/2, r/1, s/1, t/2).
+	:- dynamic(p/1, q/2, r/1, s/1, t/2).
+
+	p(X) :- q(X, Y), r(Y).
+
+	q(X, Y) :- s(X), t(X, Y).
+
+	r(a).
+	r(b).
+
+	s(1).
+	s(2).
+	s(3).
+
+	t(1, a).
+	t(2, b).
+
+:- end_object.
--- a/Logtalk/examples/metainterpreters/rules.lgt
+++ b/Logtalk/examples/metainterpreters/rules.lgt
@@ -0,0 +1,48 @@
+
+:- category(engine).
+
+	:- public(prove/1).
+
+	:- public(if/1).
+	:- dynamic(if/1).
+
+	:- op(200,  fx, if).
+	:- op(100, xfx, then).
+
+	prove(true) :-
+		!.
+
+	prove([]) :-
+		!.
+	prove([Cond| Conds]) :-
+		!,
+		prove(Cond),
+		prove(Conds).
+
+	prove(Fact) :-
+		::clause(Fact, true).
+	prove(Conclusion) :-
+		::clause(if Conds then Conclusion, true),
+		prove(Conds).
+
+:- end_category.
+
+
+:- object(rules,
+	imports(engine)).
+
+	:- public([weather/1, weekday/1, time/1, goto/1]).
+	:- dynamic([weather/1, weekday/1, time/1, goto/1]).
+
+	:- op(200,  fx, if).
+	:- op(100, xfx, then).
+
+	if [weather(sunny), weekday(weekend), time(day)] then goto(beach).
+	if [weather(raining), weekday(weekend), time(night)] then goto(cinema).
+	if [weekday(workday), time(day)] then goto(work).
+
+	weather(raining).
+	weekday(weekend).
+	time(night).
+
+:- end_object.
--- a/Logtalk/examples/metapredicates/NOTES.txt
+++ b/Logtalk/examples/metapredicates/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
@@ -8,7 +8,7 @@ Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.

 To load this example and for sample queries, please see the SCRIPT file.

-This example shows the use of metapredicates in Logtalk. Metapredicates are 
+This example shows the use of meta-predicates in Logtalk. Meta-predicates are 
 predicates whose head contains arguments that will be called as goals in the 
 body of the predicate definition.

@@ -20,5 +20,5 @@ This example defines two objects:
 		of the elements being sorted
 	
 	tracer
-		this object implements a metapredicate that is used by sort(_) to 
+		this object implements a meta-predicate that is used by sort(_) to 
 		trace the sorting algorithm steps
--- a/Logtalk/examples/metapredicates/SCRIPT.txt
+++ b/Logtalk/examples/metapredicates/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/mi/NOTES.txt
+++ b/Logtalk/examples/mi/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/mi/SCRIPT.txt
+++ b/Logtalk/examples/mi/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/miscellaneous/NOTES.txt
+++ b/Logtalk/examples/miscellaneous/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/miscellaneous/SCRIPT.txt
+++ b/Logtalk/examples/miscellaneous/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/modules/NOTES.txt
+++ b/Logtalk/examples/modules/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/modules/SCRIPT.txt
+++ b/Logtalk/examples/modules/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/msglog/NOTES.txt
+++ b/Logtalk/examples/msglog/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/msglog/SCRIPT.txt
+++ b/Logtalk/examples/msglog/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/operators/NOTES.txt
+++ b/Logtalk/examples/operators/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/operators/SCRIPT.txt
+++ b/Logtalk/examples/operators/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/parametric/NOTES
+++ b/Logtalk/examples/parametric/NOTES
@@ -1,12 +0,0 @@
-=================================================================
-Logtalk - Object oriented extension to Prolog
-Release 2.27.1
-
-Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
-=================================================================
-
-
-To load this example and for sample queries, please see the SCRIPT file.
-
-This folder contains three examples of parametric objects, the first two 
-dealing with time and date values and the third one representing rectangles.
--- a/Logtalk/examples/parametric/NOTES.txt
+++ b/Logtalk/examples/parametric/NOTES.txt
@@ -0,0 +1,12 @@
+=================================================================
+Logtalk - Object oriented extension to Prolog
+Release 2.28.2
+
+Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
+=================================================================
+
+
+To load this example and for sample queries, please see the SCRIPT file.
+
+This folder contains some examples of parametric objects, dealing with 
+lists, time and date values, and rectangles.
--- a/Logtalk/examples/parametric/SCRIPT.txt
+++ b/Logtalk/examples/parametric/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
@@ -12,6 +12,30 @@ Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 ...


+% some queries using the list parametric object:
+
+| ?- [1, 2, 3]::member(X).
+
+X = 1 ;
+X = 2 ;
+X = 3 ;
+no
+
+| ?- [1, 2, 3]::last(X).
+
+X = 3
+yes
+
+| ?- [1, 2, 3]::nextto(2, Y).
+
+Y = 3
+yes
+
+| ?- []::member(X)
+
+no
+
+
 % some queries using the time and date parametric objects:

 | ?- date(Year, Month, Day)::today.
@@ -19,14 +43,12 @@ Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 Year = 2000
 Month = 8
 Day = 15 
-
-Yes
+yes


 | ?- date(Year, _, _)::(today, \+ leap_year). 

 Year = 2002
-
 yes


@@ -35,8 +57,7 @@ yes
 Hours = 13
 Mins = 52
 Secs = 42 
-
-Yes
+yes


 | ?- R = rectangle(W, H, X, Y), R::init, R::move(3, 4, NR), NR::position(X2, Y2).
@@ -49,5 +70,4 @@ Y = 0
 NR = rectangle(2, 1, 3, 4)
 X2 = 3
 Y2 = 4 
-
-Yes
+yes
--- a/Logtalk/examples/poem/NOTES.txt
+++ b/Logtalk/examples/poem/NOTES.txt
--- a/Logtalk/examples/poem/SCRIPT.txt
+++ b/Logtalk/examples/poem/SCRIPT.txt
--- a/Logtalk/examples/points/NOTES.txt
+++ b/Logtalk/examples/points/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/points/SCRIPT.txt
+++ b/Logtalk/examples/points/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/polygons/NOTES.txt
+++ b/Logtalk/examples/polygons/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/polygons/SCRIPT.txt
+++ b/Logtalk/examples/polygons/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/profiling/NOTES.txt
+++ b/Logtalk/examples/profiling/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/profiling/SCRIPT.txt
+++ b/Logtalk/examples/profiling/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/proxies/NOTES.txt
+++ b/Logtalk/examples/proxies/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/proxies/SCRIPT.txt
+++ b/Logtalk/examples/proxies/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/puzzles/NOTES.txt
+++ b/Logtalk/examples/puzzles/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/puzzles/SCRIPT.txt
+++ b/Logtalk/examples/puzzles/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/reflection/NOTES.txt
+++ b/Logtalk/examples/reflection/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/reflection/SCRIPT.txt
+++ b/Logtalk/examples/reflection/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/relations/NOTES.txt
+++ b/Logtalk/examples/relations/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/relations/SCRIPT.txt
+++ b/Logtalk/examples/relations/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/roots/NOTES.txt
+++ b/Logtalk/examples/roots/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/roots/SCRIPT.txt
+++ b/Logtalk/examples/roots/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/searching/NOTES.txt
+++ b/Logtalk/examples/searching/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/searching/SCRIPT.txt
+++ b/Logtalk/examples/searching/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/shapes/NOTES.txt
+++ b/Logtalk/examples/shapes/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
@@ -9,6 +9,9 @@ Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 This directory contains two versions, one prototype-based and the 
 other one class-based, of a very simple geometric shapes hierarchy.

+The aim of this example is to compare the pros and cons of using 
+either prototypes or classes for defining object hierarchies.
+
 ph
 	prototype-based version

--- a/Logtalk/examples/shapes/ch/NOTES
+++ b/Logtalk/examples/shapes/ch/NOTES
@@ -1,14 +0,0 @@
-=================================================================
-Logtalk - Object oriented extension to Prolog
-Release 2.27.1
-
-Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
-=================================================================
-
-
-To load this example and for sample queries, please see the SCRIPT file.
-
-You will need to load the following files in the library directory: 
-events_loader, types_loader, and hierarchies_loader. Alternatively, 
-you may load the library all_loader file to load all library entities.
-
--- a/Logtalk/examples/shapes/ch/NOTES.txt
+++ b/Logtalk/examples/shapes/ch/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/shapes/ch/SCRIPT.txt
+++ b/Logtalk/examples/shapes/ch/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/shapes/ph/NOTES.txt
+++ b/Logtalk/examples/shapes/ph/NOTES.txt
@@ -0,0 +1,10 @@
+=================================================================
+Logtalk - Object oriented extension to Prolog
+Release 2.28.2
+
+Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
+=================================================================
+
+
+To load this example and for sample queries, please see the SCRIPT 
+file.
--- a/Logtalk/examples/shapes/ph/SCRIPT.txt
+++ b/Logtalk/examples/shapes/ph/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/sicstus/NOTES.txt
+++ b/Logtalk/examples/sicstus/NOTES.txt
@@ -0,0 +1,11 @@
+=================================================================
+Logtalk - Object oriented extension to Prolog
+Release 2.28.2
+
+Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
+=================================================================
+
+
+The examples in this folder are adopted from the SICStus Prolog manual.
+
+To load this example and for sample queries, please see the SCRIPT file.
--- a/Logtalk/examples/sicstus/SCRIPT.txt
+++ b/Logtalk/examples/sicstus/SCRIPT.txt
@@ -0,0 +1,120 @@
+=================================================================
+Logtalk - Object oriented extension to Prolog
+Release 2.28.2
+
+Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
+=================================================================
+
+
+% start by loading the necessary library support files (if not 
+% already loaded):
+
+| ?- logtalk_load([library(hierarchies_loader), library(types_loader)]).
+...
+
+
+% now you are ready for loading the example:
+
+| ?- logtalk_load(sicstus(loader)).
+...
+
+
+% try some simple queries:
+
+
+| ?- sort(rational)::sort([1/8, 2/7, 6/5, 2/9, 1/3], Sorted).
+
+Sorted = [1/8, 2/9, 2/7, 1/3, 6/5]
+yes
+
+
+| ?- sort(colours)::sort([orange, indigo, red, yellow, violet, blue, green], Sorted).
+
+Sorted = [red, orange, yellow, green, blue, indigo, violet]
+yes
+
+
+% using the pseudo-object user implies using the Prolog built-in standard 
+% order operators:
+
+| ?- sort(user)::sort([3, 1, 4, 2, 9], Sorted).
+
+Sorted = [1, 2, 3, 4, 9]
+yes
+
+
+% some messages testing object parameter passing and using:
+
+| ?- red_circle(3)::color(Color).
+
+Color = red
+yes
+
+
+| ?- red_circle(3)::area(Area).
+
+Area = 28.274334
+yes
+
+
+| ?- red_circle(3)::ancestors(As).
+
+As = [circle(3, red), ellipse(3, 3, red)]
+yes
+
+
+% show the execution context using a method (context/3) that is defined in the
+% hierarchy root and specialized (using super calls) in each descendant:
+
+| ?- red_circle(3)::context.
+
+red_circle1
+self: red_circle(3)
+this: red_circle(3)
+sender: user
+
+circle2
+self: red_circle(3)
+this: circle(3,red)
+sender: user
+
+ellipse3
+self: red_circle(3)
+this: ellipse(3,3,red)
+sender: user
+
+yes
+
+
+% send a conjunction of messages/goals to an object; just some useful syntax 
+% sugar:
+
+| ?- square(2)::(side(Side), width(Width), height(Height), area(Area)).
+
+Side = 2
+Width = 2
+Height = 2
+Area = 4
+yes
+
+
+% find all messages accepted by an object:
+
+| ?- square(2)::current_predicate(Pred).
+
+Pred = side/1 ; 
+Pred = width/1 ;
+Pred = height/1 ;
+Pred = area/1
+yes
+
+
+% find all data on a specific message accepted by an object:
+
+| ?- square(_)::predicate_property(side(_), Prop).
+
+Prop = public ;
+Prop = static ;
+Prop = declared_in(square(_133)) ;
+Prop = defined_in(square(_164))
+yes
--- a/Logtalk/examples/symdiff/NOTES.txt
+++ b/Logtalk/examples/symdiff/NOTES.txt
@@ -0,0 +1,24 @@
+=================================================================
+Logtalk - Object oriented extension to Prolog
+Release 2.28.2
+
+Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
+=================================================================
+
+
+To load this example and for sample queries, please see the SCRIPT file.
+
+This folder contains an example of using parametric objects to implement
+symbolic expression differentiation and simplification.
+
+Current limitations:
+
+	- the expression that we intend to differentiate or simplify 
+	must be a compound term. Accepted functors are *, +, -, **, and log.
+
+	- use as a variable the atom x.
+
+	- only integers can be used as constants.
+
+This example is still incomplete. For example, using sum distribution 
+property to simplify expressions is not yet implemented. 
--- a/Logtalk/examples/symdiff/SCRIPT.txt
+++ b/Logtalk/examples/symdiff/SCRIPT.txt
@@ -0,0 +1,41 @@
+=================================================================
+Logtalk - Object oriented extension to Prolog
+Release 2.28.2
+
+Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
+=================================================================
+
+
+% start by loading the example:
+
+| ?- logtalk_load(symdiff(loader)).
+...
+
+
+% simplify the expression x^1 + x0 - x1
+
+| ?- (x**1 + x*0 - x*1)::simplify(S).
+
+S = 0
+
+yes
+
+
+% differentiate and then simplify the expression 2x^3 + x^2 - 4x
+
+| ?- (2*x**3 + x**2 - 4*x)::diff(D), D::simplify(S).
+
+D = 2*(3*x**2*1)+2*x**1*1-4*1
+S = 2*(3*x**2)+2*x-4
+
+yes
+
+
+% differentiate and then simplify the expression ln(x^2 + 2x - 7) + 4x
+
+| ?- (log(x**2 + 2*x - 7) + 4*x)::diff(D), D::simplify(S).
+
+D = (2*x**1*1+2*1)*(x**2+2*x-7)** -1+4*1
+S = (2*x+2)*(x**2+2*x-7)** -1+4
+
+yes
--- a/Logtalk/examples/viewpoints/NOTES.txt
+++ b/Logtalk/examples/viewpoints/NOTES.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================
--- a/Logtalk/examples/viewpoints/SCRIPT.txt
+++ b/Logtalk/examples/viewpoints/SCRIPT.txt
@@ -1,6 +1,6 @@
 =================================================================
 Logtalk - Object oriented extension to Prolog
-Release 2.27.1
+Release 2.28.2

 Copyright (c) 1998-2006 Paulo Moura.  All Rights Reserved.
 =================================================================