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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 CList. |
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* |
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* phpcs:disable Generic.Files.LineLength.TooLong |
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*/ |
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final class CList |
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{ |
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public static function concat(): Closure |
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{ |
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return static fn (callable $xs): Closure => static fn (callable $ys): Closure => self::foldr()(self::cons())($ys)($xs); |
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} |
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public static function cons(): Closure |
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{ |
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return static fn (callable $a): Closure => static fn (callable $b): Closure => Pair::of()(Boolean::CFalse())(Pair::of()($a)($b)); |
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} |
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/** |
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* @return mixed |
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*/ |
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public static function foldl() |
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{ |
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return static fn (callable $f): Closure => static fn ($a): Closure => static fn (callable $xs) => self::foldr()( |
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static fn (callable $x): Closure => static fn (callable $g): Closure => static fn ($y) => $g($f($y)($x)) |
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)(Combinators::I())($xs)($a); |
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} |
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/** |
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* @return mixed |
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*/ |
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public static function foldr() |
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{ |
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return Combinators::Y()( |
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static fn (callable $r): Closure => static fn (callable $f): Closure => static fn ($a): Closure => static fn (callable $xs) => Boolean::CIf()(self::isNil()($xs))(static fn () => $a)(static fn () => $f(self::head()($xs))($r($f)($a)(self::tail()($xs))))() |
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); |
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} |
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public static function head(): Closure |
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{ |
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return static fn (callable $a): Closure => Pair::first()(Pair::second()($a)); |
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} |
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public static function isNil(): Closure |
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{ |
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return Pair::first(); |
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} |
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public static function length(): Closure |
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{ |
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return self::foldl()(static fn (callable $a): Closure => static fn (callable $b): Closure => Numeral::succ()($a))(Numeral::zero()); |
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} |
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public static function nil(): Closure |
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{ |
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return Pair::of()(Boolean::CTrue())(Boolean::CTrue()); |
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} |
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public static function range(): Closure |
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{ |
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return static fn (callable $a): Closure => static fn (callable $b): Closure => Numeral::minus()(Numeral::succ()($b))($a)(static fn (callable $c): Closure => CList::cons()(Numeral::minus()($b)(CList::length()($c)))($c))(CList::nil()); |
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} |
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public static function repeat(): Closure |
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{ |
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return static fn (callable $a): Closure => static fn (callable $b): Closure => $b( |
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static fn ($c): Closure => CList::cons()($a)($c) |
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)(CList::nil()); |
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} |
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public static function sum(): Closure |
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{ |
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return self::foldl()(Numeral::plus())(Numeral::zero()); |
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} |
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public static function tail(): Closure |
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{ |
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return static fn (callable $a): Closure => Pair::second()(Pair::second()($a)); |
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} |
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} |
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loophp /
church-encoding
This check looks for parameters that have been defined for a function or method, but which are not used in the method body.