On Fri, Feb 12, 2016 at 12:18 AM, Chris Angelico <rosuav@gmail.com> wrote:
Sounds like what you're looking for is a view, rather than an
additional concrete dictionary. 

If the view offers the same O(1) complexity on amortized case, then it is OK.
For the typical use in my experience (small dictionaries and several accesses) space is not a concern, so really adding a concrete dictionary like I've been doing is also fine.

João Bernardo