96 lines
2.2 KiB
Factor
96 lines
2.2 KiB
Factor
! Copyright (C) 2008 Slava Pestov.
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! See http://factorcode.org/license.txt for BSD license.
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USING: accessors arrays classes kernel sequences sets
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io prettyprint multi-methods symbols ;
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IN: boolean-expr
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! Demonstrates the use of Unicode symbols in source files, and
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! multi-method dispatch.
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TUPLE: ⋀ x y ;
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TUPLE: ⋁ x y ;
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TUPLE: ¬ x ;
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SINGLETONS: ⊤ ⊥ ;
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SINGLETONS: P Q R S T U V W X Y Z ;
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UNION: □ ⋀ ⋁ ¬ ⊤ ⊥ P Q R S T U V W X Y Z ;
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GENERIC: ⋀ ( x y -- expr )
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METHOD: ⋀ { ⊤ □ } nip ;
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METHOD: ⋀ { □ ⊤ } drop ;
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METHOD: ⋀ { ⊥ □ } drop ;
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METHOD: ⋀ { □ ⊥ } nip ;
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METHOD: ⋀ { ⋁ □ } [ [ x>> ] dip ⋀ ] [ [ y>> ] dip ⋀ ] 2bi ⋁ ;
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METHOD: ⋀ { □ ⋁ } [ x>> ⋀ ] [ y>> ⋀ ] 2bi ⋁ ;
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METHOD: ⋀ { □ □ } \ ⋀ boa ;
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GENERIC: ⋁ ( x y -- expr )
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METHOD: ⋁ { ⊤ □ } drop ;
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METHOD: ⋁ { □ ⊤ } nip ;
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METHOD: ⋁ { ⊥ □ } nip ;
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METHOD: ⋁ { □ ⊥ } drop ;
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METHOD: ⋁ { □ □ } \ ⋁ boa ;
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GENERIC: ¬ ( x -- expr )
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METHOD: ¬ { ⊤ } drop ⊥ ;
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METHOD: ¬ { ⊥ } drop ⊤ ;
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METHOD: ¬ { ⋀ } [ x>> ¬ ] [ y>> ¬ ] bi ⋁ ;
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METHOD: ¬ { ⋁ } [ x>> ¬ ] [ y>> ¬ ] bi ⋀ ;
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METHOD: ¬ { □ } \ ¬ boa ;
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: → ( x y -- expr ) ¬ ⋀ ;
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: ⊕ ( x y -- expr ) [ ⋁ ] [ ⋀ ¬ ] 2bi ⋀ ;
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: ≣ ( x y -- expr ) [ ⋀ ] [ [ ¬ ] bi@ ⋀ ] 2bi ⋁ ;
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GENERIC: (cnf) ( expr -- cnf )
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METHOD: (cnf) { ⋀ } [ x>> (cnf) ] [ y>> (cnf) ] bi append ;
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METHOD: (cnf) { □ } 1array ;
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GENERIC: cnf ( expr -- cnf )
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METHOD: cnf { ⋁ } [ x>> cnf ] [ y>> cnf ] bi append ;
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METHOD: cnf { □ } (cnf) 1array ;
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GENERIC: satisfiable? ( expr -- ? )
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METHOD: satisfiable? { ⊤ } drop t ;
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METHOD: satisfiable? { ⊥ } drop f ;
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: partition ( seq quot -- left right )
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[ [ not ] compose filter ] [ filter ] 2bi ; inline
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: (satisfiable?) ( seq -- ? )
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[ \ ¬ instance? ] partition [ x>> ] map intersect empty? ;
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METHOD: satisfiable? { □ }
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cnf [ (satisfiable?) ] contains? ;
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GENERIC: (expr.) ( expr -- )
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METHOD: (expr.) { □ } pprint ;
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: op. ( expr -- )
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"(" write
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[ x>> (expr.) ]
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[ bl class pprint bl ]
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[ y>> (expr.) ]
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tri
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")" write ;
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METHOD: (expr.) { ⋀ } op. ;
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METHOD: (expr.) { ⋁ } op. ;
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METHOD: (expr.) { ¬ } [ class pprint ] [ x>> (expr.) ] bi ;
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: expr. ( expr -- ) (expr.) nl ;
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