I attempted to search and experiment, but I couldn't determine how to incorporate Slim into Ruby on Rails' statistics for views. Currently, it only counts .erb templates, whereas I also want .slim files to be included since they are also considered views.
% bin/rails stats
+----------------------+--------+--------+---------+---------+-----+-------+
| Name | Lines | LOC | Classes | Methods | M/C | LOC/M |
+----------------------+--------+--------+---------+---------+-----+-------+
| Controllers | 3245 | 1634 | 57 | 218 | 3 | 5 |
| Helpers | 186 | 149 | 0 | 18 | 0 | 6 |
| Jobs | 34 | 20 | 2 | 2 | 1 | 8 |
| Models | 879 | 541 | 25 | 77 | 3 | 5 |
| Mailers | 85 | 53 | 3 | 6 | 2 | 6 |
| Channels | 46 | 28 | 3 | 4 | 1 | 5 |
| Views | 0 | 0 | 0 | 0 | 0 | 0 |
+----------------------+--------+--------+---------+---------+-----+-------+
I could add an extra rules for something like "Slim views", but this would count the .erb templates in views too.