src/Language.php
public static function getLongCode($short = 'default')
    {
        if ($short == 'default') {
            $short = app()->getLocale();
        }

        $long = 'en-GB';

        // Get languages from config
        $languages = config('language.all');

        foreach ($languages as $language) {
            if ($language['short'] != $short) {
                continue;
            }

            $long = $language['long'];
        }

        return $long;
    }
public static function getLongCode($short = 'default')
    {
        if ($short == 'default') {
            $short = app()->getLocale();
        }

        $long = 'en-GB';

        // Get languages from config
        $languages = config('language.all');

        foreach ($languages as $language) {
            if ($language['short'] != $short) {
                continue;
            }

            $long = $language['long'];
        }

        return $long;
    }
Returns the language long code.

@param string $short

@return string