>> What would be the way to define-or-set that a specific hash has
>> non-case-sensitive keys?
> There are two things in this:
> (1) The syntax to type the keys of a hash---too bad that I forgot it
> and currently don't find it in the Synopsyses. Pointers welcome!
> (2) A way to constrain a string to be case insensitive.
Yes, but also auto-normalization of incoming keys. Maybe like
Hash::Case::Preserve (=tie). Yes, maybe by an exception (on the type).