Concepts: Typeclasses for C++?

I’ve had a hypothesis for a while that C++ templates (paired at times with ADL) are an ad-hoc, unsound version of typeclasses. I’ve seen this hold for┬áparser combinators, range base algorithms, and more. I’m also not the first to draw this comparison[1]. Concepts are supposed to bring soundness in through constrained templates. Concepts look awfully …