I haven&#x27;t coded in C++ for a very long time, but won&#x27;t any implementation of that function, and additional templated functions which call it,  only get checked at template expansion time? As I understand, buggy templated functions and classes can go unnoticed in a codebase or library simply because no-one has instantiated them in a way which exposes the bug. This is definitely not the case for Idris.<p>My understanding was that concepts began as an attempt to fix this &quot;problem&quot;.