The challenge is that if the program is busy in a spin loop, there's no way to preempt it and modify it. Things like malloc, spin loops, network requests, syscalls etc.

I looked into liveplusplus a lot and their unreal integration also requires a broker to get the most out of it. If you're building a game engine and want to support struct layout and alignment changes, you'll need to do some re-instancing. Hiding a `subsecond::call` deep in the bowels of the host framework hides it from the user and lets the framework handle any complicated state management it needs during hotpatches.

I wouldn't say it's purity - the first version of subsecond actually did do in-process modification - but after playing around with it for a while, I much preferred the light runtime integration. The dioxus integration was about 5 lines of code, so it's quite minimal.