101 lines
1.6 KiB
Plaintext
101 lines
1.6 KiB
Plaintext
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=================================================================
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Logtalk - Object oriented extension to Prolog
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Release 2.28.2
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Copyright (c) 1998-2006 Paulo Moura. All Rights Reserved.
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=================================================================
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% start by loading the example:
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| ?- logtalk_load(metainterpreters(loader)).
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...
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% direct call of p/1:
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| ?- ?- database::p(X).
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X = 1 ;
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X = 2
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yes
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% solver - a simple meta-interpreter for pure Prolog:
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| ?- database::solve(p(X)).
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X = 1 ;
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X = 2
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yes
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| ?- database::proof_tree(p(X), Tree).
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X = 1
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Tree = p(1):- (q(1, a):- (s(1):-true), (t(1, a):-true)), (r(a):-true) ;
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X = 2
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Tree = p(2):- (q(2, b):- (s(2):-true), (t(2, b):-true)), (r(b):-true)
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yes
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% tracer - a simple meta-interpreter for tracing goal proofs using pure Prolog:
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| ?- database::trace(p(X)).
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1 call: p(_G180)
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2 call: q(_G180, _G316)
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3 call: s(_G180)
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3 exit: s(1)
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3 call: t(1, _G316)
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3 exit: t(1, a)
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2 exit: q(1, a)
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2 call: r(a)
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2 exit: r(a)
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1 exit: p(1)
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X = 1 ;
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1 redo: p(1)
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2 redo: r(a)
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2 fail: r(a)
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2 redo: q(1, a)
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3 redo: t(1, a)
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3 fail: t(1, _G316)
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3 redo: s(1)
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3 exit: s(2)
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3 call: t(2, _G316)
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3 exit: t(2, b)
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2 exit: q(2, b)
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2 call: r(b)
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2 exit: r(b)
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1 exit: p(2)
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X = 2 ;
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1 redo: p(2)
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2 redo: r(b)
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2 fail: r(b)
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2 redo: q(2, b)
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3 redo: t(2, b)
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3 fail: t(2, _G316)
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3 redo: s(2)
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3 exit: s(3)
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3 call: t(3, _G316)
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3 fail: t(3, _G316)
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3 redo: s(3)
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3 fail: s(_G180)
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2 fail: q(_G180, _G316)
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1 fail: p(_G180)
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no
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% another example: expert system rules:
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| rules::prove(weather(Wheather)).
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Wheather = raining
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yes
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| ?- rules::prove(goto(Where)).
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Where = cinema
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yes
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