diff --git a/src/Annotations.php b/src/Annotations.php
index a2c4f5f..fdbe5a4 100644
--- a/src/Annotations.php
+++ b/src/Annotations.php
@@ -27,17 +27,15 @@ class Annotations
 	/** @internal identifier */
 	public const RE_IDENTIFIER = '[_a-zA-Z\x7F-\xFF][_a-zA-Z0-9\x7F-\xFF-\\\]*';
 
-	/** @var bool */
-	public static $useReflection;
+	public static ?bool $useReflection = null;
 
-	/** @var bool */
-	public static $autoRefresh = true;
+	public static bool $autoRefresh = true;
 
 	/** @var string[] */
-	public static $inherited = ['description', 'param', 'return'];
+	public static array $inherited = ['description', 'param', 'return'];
 
 	/** @var array<string, array<string, array<string, array<mixed>>>> */
-	private static $cache;
+	private static array $cache;
 
 	/**
 	 * @param ReflectionClass<object>|ReflectionMethod|ReflectionProperty|ReflectionFunction $r
@@ -49,9 +47,8 @@ public static function hasAnnotation(Reflector $r, string $name): bool
 
 	/**
 	 * @param ReflectionClass<object>|ReflectionMethod|ReflectionProperty|ReflectionFunction $r
-	 * @return mixed
 	 */
-	public static function getAnnotation(Reflector $r, string $name)
+	public static function getAnnotation(Reflector $r, string $name): mixed
 	{
 		$res = self::getAnnotations($r);
 
@@ -93,14 +90,12 @@ public static function getAnnotations(Reflector $r): array
 			return self::$cache[$type][$member];
 		}
 
-		if (self::$useReflection) {
-			$annotations = self::parseComment((string) $r->getDocComment());
-		} else {
-			$annotations = [];
-		}
+		$annotations = self::$useReflection ? self::parseComment((string) $r->getDocComment()) : [];
 
-		// @phpstan-ignore-next-line
-		if ($r instanceof ReflectionMethod && !$r->isPrivate() && (!$r->isConstructor() || !empty($annotations['inheritdoc'][0]))
+		if (
+			$r instanceof ReflectionMethod && !$r->isPrivate()
+			&& (!$r->isConstructor() || !empty($annotations['inheritdoc'][0])) // @phpstan-ignore-line
+			&& $type !== null
 		) {
 			try {
 				$inherited = self::getAnnotations(new ReflectionMethod((string) get_parent_class($type), $member));
diff --git a/src/Csv.php b/src/Csv.php
index 8ed02e5..7ac8a3d 100644
--- a/src/Csv.php
+++ b/src/Csv.php
@@ -75,11 +75,10 @@ public static function structural(array $scheme, string $file, string $delimiter
 	}
 
 	/**
-	 * @param mixed $value
 	 * @param mixed[][] $liner
 	 * @param string[] $keys
 	 */
-	protected static function matchValue($value, array &$liner, array $keys): void
+	protected static function matchValue(mixed $value, array &$liner, array $keys): void
 	{
 		if (count($keys) > 1) {
 			$tmp = array_shift($keys);
diff --git a/src/DateTime.php b/src/DateTime.php
index f16af49..6da2c9a 100644
--- a/src/DateTime.php
+++ b/src/DateTime.php
@@ -6,6 +6,9 @@
 use DateTimeZone;
 use Nette\Utils\DateTime as NetteDateTime;
 
+/**
+ * @phpstan-consistent-constructor
+ */
 class DateTime extends NetteDateTime
 {
 
@@ -14,77 +17,12 @@ public function __construct(string $time = 'now', ?DateTimeZone $timezone = null
 		parent::__construct($time, $timezone);
 	}
 
-	/**
-	 * @param string|int|DateTimeInterface $time
-	 * @return static
-	 */
-	public static function from($time): self
+	public static function from(string|int|DateTimeInterface|null $time): static
 	{
 		return parent::from($time);
 	}
 
-	/**
-	 * @return static
-	 */
-	public function modifyClone(string $modify = ''): self
-	{
-		return parent::modifyClone($modify);
-	}
-
-	/**
-	 * Set time to current time
-	 *
-	 * @return static
-	 */
-	public function setCurrentTime(): self
-	{
-		return $this->modifyClone()->setTime((int) date('H'), (int) date('i'), (int) date('s'));
-	}
-
-	/**
-	 * Reset current time (00:00:00)
-	 *
-	 * @return static
-	 */
-	public function resetTime(): self
-	{
-		return $this->modifyClone()->setTime(0, 0, 0);
-	}
-
-	/**
-	 * Reset current time (00:00:00)
-	 *
-	 * @return static
-	 */
-	public function setZeroTime(): self
-	{
-		return $this->resetTime();
-	}
-
-	/**
-	 * Set time to midnight (23:59:59)
-	 *
-	 * @return static
-	 */
-	public function setMidnight(): self
-	{
-		return $this->modifyClone()->setTime(23, 59, 59);
-	}
-
-	/**
-	 * Set date to today
-	 *
-	 * @return static
-	 */
-	public function setToday(): self
-	{
-		return $this->modifyClone()->setDate((int) date('Y'), (int) date('m'), (int) date('d'));
-	}
-
-	/**
-	 * @return static
-	 */
-	public static function createBy(?int $year = null, ?int $month = null, ?int $day = null, ?int $hour = null, ?int $minute = null, ?int $second = null): self
+	public static function createBy(?int $year = null, ?int $month = null, ?int $day = null, ?int $hour = null, ?int $minute = null, ?int $second = null): static
 	{
 		return self::create([
 			'year' => $year,
@@ -98,9 +36,8 @@ public static function createBy(?int $year = null, ?int $month = null, ?int $day
 
 	/**
 	 * @param string[]|int[]|null[] $args
-	 * @return static
 	 */
-	public static function create(array $args): self
+	public static function create(array $args): static
 	{
 		$date = new static();
 
@@ -134,55 +71,82 @@ public static function create(array $args): self
 		return $date;
 	}
 
+	public function modifyClone(string $modify = ''): static
+	{
+		return parent::modifyClone($modify);
+	}
+
 	/**
-	 * @return static
+	 * Set time to current time
 	 */
-	public function getFirstDayOfWeek(): self
+	public function setCurrentTime(): static
 	{
-		return $this->modifyClone('this week')
-			->setZeroTime();
+		return $this->modifyClone()->setTime((int) date('H'), (int) date('i'), (int) date('s'));
 	}
 
 	/**
-	 * @return static
+	 * Reset current time (00:00:00)
 	 */
-	public function getLastDayOfWeek(): self
+	public function resetTime(): static
 	{
-		return $this->modifyClone('this week +6 days')
-			->setMidnight();
+		return $this->modifyClone()->setTime(0, 0, 0);
 	}
 
 	/**
-	 * @return static
+	 * Reset current time (00:00:00)
 	 */
-	public function getFirstDayOfMonth(): self
+	public function setZeroTime(): static
 	{
-		return $this->modifyClone('first day of this month')
-			->setZeroTime();
+		return $this->resetTime();
 	}
 
 	/**
-	 * @return static
+	 * Set time to midnight (23:59:59)
 	 */
-	public function getLastDayOfMonth(): self
+	public function setMidnight(): static
 	{
-		return $this->modifyClone('last day of this month')
-			->setMidnight();
+		return $this->modifyClone()->setTime(23, 59, 59);
 	}
 
 	/**
-	 * @return static
+	 * Set date to today
 	 */
-	public function getFirstDayOfYear(): self
+	public function setToday(): static
+	{
+		return $this->modifyClone()->setDate((int) date('Y'), (int) date('m'), (int) date('d'));
+	}
+
+	public function getFirstDayOfWeek(): static
+	{
+		return $this->modifyClone('this week')
+			->setZeroTime();
+	}
+
+	public function getLastDayOfWeek(): static
+	{
+		return $this->modifyClone('this week +6 days')
+			->setMidnight();
+	}
+
+	public function getFirstDayOfMonth(): static
+	{
+		return $this->modifyClone('first day of this month')
+			->setZeroTime();
+	}
+
+	public function getLastDayOfMonth(): static
+	{
+		return $this->modifyClone('last day of this month')
+			->setMidnight();
+	}
+
+	public function getFirstDayOfYear(): static
 	{
 		return $this->modifyClone(sprintf('first day of January %s', $this->format('Y')))
 			->setZeroTime();
 	}
 
-	/**
-	 * @return static
-	 */
-	public function getLastDayOfYear(): self
+	public function getLastDayOfYear(): static
 	{
 		return $this->modifyClone(sprintf('last day of December %s', $this->format('Y')))
 			->setMidnight();
diff --git a/src/Deeper.php b/src/Deeper.php
index 281fc8b..f5a788a 100644
--- a/src/Deeper.php
+++ b/src/Deeper.php
@@ -17,6 +17,7 @@ public static function has($key, array $arr, string $sep = '.'): bool
 	{
 		try {
 			static::get($key, $arr, $sep);
+
 			return true;
 		} catch (InvalidArgumentException $e) {
 			return false;
@@ -41,23 +42,16 @@ public static function get($key, array $arr, string $sep = '.', $default = null)
 	}
 
 	/**
-	 * @param string|int|bool|null $key
 	 * @param non-empty-string $sep
 	 * @return string[]
 	 */
-	public static function flat($key, string $sep = '.'): array
+	public static function flat(string|int|bool|null $key, string $sep = '.'): array
 	{
 		if ($key === '' || $key === null || $key === false) {
 			return [];
 		}
 
-		$res = explode($sep, (string) $key);
-
-		if ($res === false) {
-			return [];
-		}
-
-		return $res;
+		return explode($sep, (string) $key);
 	}
 
 }
diff --git a/src/Fields.php b/src/Fields.php
index 5a215ea..48dd468 100644
--- a/src/Fields.php
+++ b/src/Fields.php
@@ -5,10 +5,7 @@
 class Fields
 {
 
-	/**
-	 * @return mixed
-	 */
-	public static function inn(string $s)
+	public static function inn(string $s): mixed
 	{
 		$s = Strings::spaceless($s);
 		$s = Strings::dashless($s);
@@ -17,10 +14,7 @@ public static function inn(string $s)
 		return $s;
 	}
 
-	/**
-	 * @return mixed
-	 */
-	public static function tin(string $s)
+	public static function tin(string $s): mixed
 	{
 		$s = Strings::spaceless($s);
 		$s = Strings::dashless($s);
@@ -29,10 +23,7 @@ public static function tin(string $s)
 		return $s;
 	}
 
-	/**
-	 * @return mixed
-	 */
-	public static function zip(string $s)
+	public static function zip(string $s): mixed
 	{
 		$s = Strings::spaceless($s);
 		$s = Strings::dashless($s);
@@ -40,10 +31,7 @@ public static function zip(string $s)
 		return $s;
 	}
 
-	/**
-	 * @return mixed
-	 */
-	public static function phone(string $s)
+	public static function phone(string $s): mixed
 	{
 		$s = Strings::spaceless($s);
 		$s = Strings::dashless($s);
diff --git a/src/Http.php b/src/Http.php
index 4689f80..040e043 100644
--- a/src/Http.php
+++ b/src/Http.php
@@ -10,8 +10,7 @@ class Http
 
 	use StaticClass;
 
-	/** @var string */
-	private static $metadataPattern = '
+	private static string $metadataPattern = '
 		~<\s*meta\s
 
 		# using lookahead to capture type to $1
@@ -39,7 +38,7 @@ public static function metadata(string $content): array
 		if (preg_match_all(self::$metadataPattern, $content, $matches) !== false) {
 			$combine = array_combine($matches[1], $matches[2]);
 
-			if ($combine === false) {
+			if ($combine === []) {
 				throw new LogicException('Matches count is not equal.');
 			}
 
diff --git a/src/LazyCollection.php b/src/LazyCollection.php
index 5321122..c72e78e 100644
--- a/src/LazyCollection.php
+++ b/src/LazyCollection.php
@@ -7,6 +7,7 @@
 
 /**
  * @implements IteratorAggregate<int, mixed>
+ * @phpstan-consistent-constructor
  */
 class LazyCollection implements IteratorAggregate
 {
@@ -15,7 +16,7 @@ class LazyCollection implements IteratorAggregate
 	private $callback;
 
 	/** @var mixed[] */
-	private $data = null;
+	private ?array $data = null;
 
 	private function __construct(callable $callback)
 	{
diff --git a/src/Merger.php b/src/Merger.php
index 6ae56db..d85ec78 100644
--- a/src/Merger.php
+++ b/src/Merger.php
@@ -5,12 +5,7 @@
 class Merger
 {
 
-	/**
-	 * @param mixed $left
-	 * @param mixed $right
-	 * @return mixed
-	 */
-	public static function merge($left, $right)
+	public static function merge(mixed $left, mixed $right): mixed
 	{
 		if (is_array($left) && is_array($right)) {
 			foreach ($left as $key => $val) {
diff --git a/src/Monad/Optional.php b/src/Monad/Optional.php
index 388e7ad..0e7dee3 100644
--- a/src/Monad/Optional.php
+++ b/src/Monad/Optional.php
@@ -5,31 +5,27 @@
 use Nette\InvalidStateException;
 use Throwable;
 
+/**
+ * @phpstan-consistent-constructor
+ */
 class Optional
 {
 
-	/** @var mixed */
-	private $value;
+	private mixed $value;
 
-	/** @var mixed */
-	private $elseValue;
+	private mixed $elseValue = null;
 
-	/** @var Throwable */
-	private $elseThrow;
+	private ?Throwable $elseThrow = null;
 
-	/**
-	 * @param mixed $value
-	 */
-	protected function __construct($value)
+	protected function __construct(mixed $value)
 	{
 		$this->value = $value;
 	}
 
 	/**
-	 * @param mixed $value
 	 * @return static
 	 */
-	public static function of($value): self
+	public static function of(mixed $value): self
 	{
 		return new static($value);
 	}
@@ -48,10 +44,9 @@ public function isPresent(): bool
 	}
 
 	/**
-	 * @param mixed $value
 	 * @return static
 	 */
-	public function orElse($value): self
+	public function orElse(mixed $value): self
 	{
 		$this->elseValue = $value;
 
@@ -68,10 +63,7 @@ public function orElseThrow(Throwable $e): self
 		return $this;
 	}
 
-	/**
-	 * @return mixed
-	 */
-	public function get()
+	public function get(): mixed
 	{
 		if ($this->value !== null) {
 			return $this->value;
diff --git a/src/Urls.php b/src/Urls.php
index eecd5cb..03ee74b 100644
--- a/src/Urls.php
+++ b/src/Urls.php
@@ -7,7 +7,7 @@ class Urls
 
 	public static function hasFragment(string $url): bool
 	{
-		return Strings::contains($url, '#');
+		return str_contains($url, '#');
 	}
 
 }
diff --git a/src/Values/Email.php b/src/Values/Email.php
index 57f8951..c6cd6ca 100644
--- a/src/Values/Email.php
+++ b/src/Values/Email.php
@@ -9,11 +9,9 @@
 class Email
 {
 
-	/** @var string */
-	private $domainPart;
+	private string $domainPart;
 
-	/** @var string */
-	private $localPart;
+	private string $localPart;
 
 	public function __construct(string $value)
 	{