In Zig's case you pass the argument whether or not it's asynchronous, though. The caller controls the behavior, not the function being called.

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layer8 5 hours ago | parent [-]

The coloring is not the concrete argument (Io implementation) that is passed, but whether the function has an Io parameter in the first place. Whether the implementation of a function performs IO is in principle an implementation detail that can change in the future. A function that doesn't take an Io argument but wants to call another function that requires an Io argument can't. So you end up adding Io parameters just in case, and in turn require all callers to do the same. This is very much like function coloring.

In a language with objects or closures (which Zig doesn't have first-class support for), one flexibility benefit of the Io object approach is that you can move it to object/closure creation and keep the function/method signature free from it. Still, you have to pass it somewhere.

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messe 3 hours ago | parent | next [-]

> Whether the implementation of a function performs IO is in principle an implementation detail that can change in the future.

I think that's where your perspective differs from Zig developers.

Performing IO, in my opinion, is categorically not an implementation detail. In the same way that heap allocation is not an implementation detail in idiomatic Zig.

I don't want to find out my math library is caching results on disk, or allocating megabytes to memoize. I want to know what functions I can use in a freestanding environment, or somewhere resource constrained.

	▲	simonask 24 minutes ago \| parent [-]
		This is also why function coloring is not a problem, and is in fact desirable a lot of the time.

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2 hours ago | parent | prev | next [-]

[deleted]

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derriz 3 hours ago | parent | prev | next [-]

> A function that doesn't take an Io argument but wants to call another function that requires an Io argument can't.

Why? Can’t you just create an instance of an Io of whatever flavor you prefer and use that? Or keep one around for use repeatedly?

The whole “hide a global event loop behind language syntax” is an example of a leaky abstraction which is also restrictive. The approach here is explicit and doesn’t bind functions to hidden global state.

	▲	layer8 3 hours ago \| parent [-]
		You can, but then you’re denying your callers control over the Io. It’s not really different with async function coloring: https://news.ycombinator.com/item?id=46126310 Scheduling of IO operations isn’t hidden global state. Or if it is, then so is thread scheduling by the OS.

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quantummagic 4 hours ago | parent | prev [-]

Is that a problem in practice though? Zig already has this same situation with its memory allocators; you can't allocate memory unless you take a parameter. Now you'll just have to take a memory allocator AND an additional io object. Doesn't sound very ergonomic to me, but if all Zig code conforms to this scheme, in practice there will only-one-way-to-do-it. So one of the colors will never be needed, or used.