There really should be a syntactic sugar for things like pure function/stateless, and its collary, explicitly reentrant, verified by the compiler. Then a debug

There really should be a syntactic sugar for things like pure function/stateless, and its collary, explicitly reentrant, verified by the compiler. Then a debug mode- or perhaps flag would allow all functions which dont qualify as explicitly non-threadsafe, possibly having that as the default. But I'm dubious about the use of needing to explicitly mark functions as non-threadsafe, its a bit like the const vs mut, but while const might be slightly less common save for things that should be autogenerated, in the case of reentrant, if it isnt explicitly marked, it should never be used reentrant, even if it happens to be a pure function at the moment, or for this one implementation etc.