PHPStan\Analyser\Scope::getAnonymousFunctionType PHP Method

    private function getAnonymousFunctionType($type = null, bool $isNullable) : Type
    {
        if ($type === null) {
            return new MixedType(true);
        } elseif ($type === 'string') {
            return new StringType($isNullable);
        } elseif ($type === 'int') {
            return new IntegerType($isNullable);
        } elseif ($type === 'bool') {
            return new BooleanType($isNullable);
        } elseif ($type === 'float') {
            return new FloatType($isNullable);
        } elseif ($type === 'callable') {
            return new CallableType($isNullable);
        } elseif ($type === 'array') {
            return new ArrayType(new MixedType(true), $isNullable);
        } elseif ($type instanceof Name) {
            $className = (string) $type;
            if ($className === 'self') {
                $className = $this->getClass();
            }
            return new ObjectType($className, $isNullable);
        }
        return new MixedType($isNullable);
    }