It's true that you can write arbitrary code in the template and reference other gems if needed. However, to reference constants located in any directory of your

It's true that you can write arbitrary code in the template and reference other gems if needed. However, to reference constants located in any directory of your application, such as `app/` or `lib/`, you'd need to either explicitly require these files, overtaking the eager- or auto-loading mechanism of your app framework, or boot the whole application. So, you're right that it's not impossible, but it requires some additional considerations.