Boolean implementation in PHP

Boolean.php

<?php

declare(strict_types=1);

namespace Marcosh\PhpValidationDSL;

final class Boolean
{
    /** @var Bool */
    private $isTrue;

    private function __construct(bool $isTrue)
    {
        $this->isTrue = $isTrue;
    }

    public static function true(): self
    {
        return new self(true);
    }

    public static function false(): self
    {
        return new self(false);
    }

    /**
     * @template T
     * @param mixed $ifTrue
     * @param mixed $ifFalse
     * @psalm-param T $ifTrue
     * @psalm-param T $ifFalse
     * @return mixed
     * @psalm-return T
     */
    public function evalBool($ifTrue, $ifFalse)
    {
        if ($this->isTrue) {
            return $ifTrue;
        }

        return $ifFalse;
    }

    public function fromEnum(): int
    {
        return $this->evalBool(1, 0);
    }

    public function show(): string
    {
        return $this->evalBool('true', 'false');
    }

    public function compare(self $that): Ordering
    {
        return $this->evalBool(
            $that->evalBool(Ordering::EQ(), Ordering::GT()),
            $that->evalBool(Ordering::LT(), Ordering::EQ())
        );
    }

    public function and(self $that): self
    {
        return $this->evalBool(
            $that->evalBool(self::true(), self::false()),
            $that->evalBool(self::false(), self::false())
        );
    }

    public function or(self $that): self
    {
        return $this->evalBool(
            $that->evalBool(self::true(), self::true()),
            $that->evalBool(self::true(), self::false())
        );
    }

    public function not(): self
    {
        return $this->evalBool(self::false(), self::true());
    }
}