C++Now 2021

Concepts may appear easy to use on the surface, but there are a number of traps you can fall into when using them in your generic library. The problems we will be discussing basically boil down to: "I wrote my template library, I tested it on all the types I could think of, but it failed to work with my users' types."

In this session we will see two such traps, and how to remedy them.
1. Using more of types' interface than what the concept declares -- remedied by using concept archetypes.
2. Failure to communicate semantic requirements -- sometimes remedied by emulating semantic constraints with syntactic constraints.

This is a live coding session. It will be assumed that you are already familiar with C++20 concepts. There will be only a super-brief introduction to concepts.