> To me it feels very similar to an interface (trait) implemented by a bunch of classes (structs) Then you might not fully grok sum types yet. > From my persp

> To me it feels very similar to an interface (trait) implemented by a bunch of classes (structs) Then you might not fully grok sum types yet. > From my perspective a discriminant vs a vtable pointer is a boring implementation detail the compiler should just figure out for me based on what would be more optimal in a given situation. Disagree. It's a design choice that should be decided by the programmers. There's a tradeoff—choosing which should be easier: adding a new variant or adding a new function/method. It's called the Expression Problem: https://wiki.c2.com/?ExpressionProblem https://wiki.c2.com/?ExpressionProblem