Comment by flohofwoe

> This is also true for Zig: Red functions require an Io argument. Blue functions do not. Calling a red function means you need to have an Io argument.

I don't think that's necessarily true. Like with allocators, it should be possible to pass the IO pointer into a library's init function once, and then use that pointer in any library function that needs to do IO. The Zig stdlib doesn't use that approach anymore for allocators, but not because of technical restrictions but for 'transparency' (it's immediately obvious which function allocates under the hood and which doesn't).

Now the question is, does an IO parameter in a library's init function color the entire library, or only the init function? ;P

PS: you could even store the IO pointer in a public global making it visible to all code that needs to do IO, which makes the coloring question even murkier. It will be interesting though how the not-yet-implemented stackless coroutine (e.g. 'code-transform-async') IO system will deal with such situations.