Many languages propose a system of ranges:

    case 'a' .. 'z', 'A' .. 'Z', '0' .. '9', '_': ...;

although when working with enumerators, there is a still a risk caused by the fact that re-ordering enumerators or adding new ones can break the switches.

Despite of the drawback I prefer. Also a Range can be a formal expression which simplifies the grammar of other sub-expressions and statements, not only switches but also array slices, tuple slices, foreach, literal bitsets, etc.