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<?php |
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/** |
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* For the full copyright and license information, please view |
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* the LICENSE file that was distributed with this source code. |
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*/ |
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declare(strict_types=1); |
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namespace loophp\churchencoding; |
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use Closure; |
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use loophp\combinator\Combinators; |
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/** |
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* Class Boolean. |
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* |
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* phpcs:disable Generic.Files.LineLength.TooLong |
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*/ |
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final class Boolean |
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{ |
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public static function CAnd(): Closure |
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{ |
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return static fn (callable $l): Closure => static fn (callable $c): Closure => $l($c)(self::CFalse()); |
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} |
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public static function CFalse(): Closure |
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{ |
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return Combinators::Ki(); |
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} |
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public static function CIf(): Closure |
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{ |
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return Combinators::I(); |
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} |
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public static function CNot(): Closure |
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{ |
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return Combinators::C(); |
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} |
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public static function COr(): Closure |
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{ |
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return Combinators::M(); |
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} |
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public static function CTrue(): Closure |
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{ |
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return Combinators::K(); |
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} |
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public static function CXor(): Closure |
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{ |
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return static fn (callable $a): Closure => static fn (callable $b): Closure => ($a($b(self::CFalse())(self::CTrue())))($b(self::CTrue())(self::CFalse())); |
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} |
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public static function eq(): Closure |
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{ |
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return static fn (callable $a): Closure => static fn (callable $b): Closure => self::CAnd()(self::lte()($a)($b))(self::lte()($b)($a)); |
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} |
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public static function gt(): Closure |
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{ |
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return static fn (callable $a): Closure => static fn (callable $b): Closure => self::CNot()(self::lte()($a)($b)); |
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} |
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public static function gte(): Closure |
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{ |
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return static fn (callable $a): Closure => static fn (callable $b): Closure => self::isZero()(Numeral::minus()($b)($a)); |
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} |
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public static function isZero(): Closure |
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{ |
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return static fn (callable $a): Closure => $a(Combinators::K()(self::CFalse()))(self::CTrue()); |
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} |
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public static function lt(): Closure |
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{ |
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return static fn (callable $a): Closure => static fn (callable $b): Closure => self::CNot()(self::gte()($a)($b)); |
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} |
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public static function lte(): Closure |
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{ |
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return static fn (callable $a): Closure => static fn (callable $b): Closure => self::isZero()(Numeral::minus()($a)($b)); |
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} |
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} |
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loophp /
church-encoding
