3 ms·
> It's quite rare for a function to unexpectedly gain a dependency on ... If this was true in general, the function coloring problem wouldn't be talked about.
by dminik 1y ago
> It's quite rare for a function to unexpectedly gain a dependency on ...
If this was true in general, the function coloring problem wouldn't be talked about.
However, the second point is more interesting. I think there's a bit of a Stockholm syndrome thing here with Zig programmers and Allocator. It's likely that Zig programmers won't mind passing around an extra param.
If anything, it would make sense to me to have IO contain an allocator too. Allocation is a kind of IO too. But I guess it's going to be 2 params from now on.
- throwawaymaths 1y ago> But I guess it's going to be 2 params from now on. >> So, if you discover that a code path you previously thought was pure actually does need to perform IO, then you don't need to apply some nasty viral change; you just grab `my_thing.io
- camgunz 1y agoPython, for example, will let you call async functions inside non-async functions, you just have to set up the event loop yourself. This isn't conceptually different than the Io thing here.
- throwawaymaths 1y agoexcept you cant "pass the same event loop in multiple locations". its also not an easy lift. the zig std will provide a few standard implementations which would be trivial to drop in.
- camgunz 1y agoI thought it was the exact same; an event loop in Python is just whatever Io is in Zig, make it a param, get it from an import and a lookup (`import asyncio; loop = asyncio.get_running_loop()`). I might be misunderstanding what you're saying though.
- deleted 1y ago[deleted]
- throwawaymaths 1y agohm maybe. i guess ive only used python in situations where it injects it into amain so i could have been confused. i thought python async was a wrapper around generators, and so the mechanism cant be instantiated in multiple places. i stand corrected.
- camgunz 1y agoOh no you're right it's a pain in the ass and weird. But I think it's the way because there's no good reason to have more than one event loop. Also... maybe it started out as generator wrappers? I think I read something that said that.
- Spivak 1y ago> no good reason to have more than one event loop Per thread—once you start working in multiple threads you have the choice to have one global event loop, which comes at the cost of all async code being effectively serialized as far as threads are concerned*, or one event loop per thread. * Which can be fine if your program is mostly not async but you have that one stubborn library. Yay async virality.
- camgunz 1y agoI can't say there's no good reason to have per thread event loops, but I think I can say if you do know of one you're suffering a terrible curse. I can only imagine the constraints that would force me to do this.
- Spivak 1y agoBecause you have a main application running a web server and a daemon worker thread performing potentially long running tasks that use async libraries and you don't want to block the responsiveness of your web server. It's really not that bad, at least in Python.
- gpderetta 1y agoBut the asyncio event loop is not reentrant, so your faux sync functions cannot be safely called from other async functions. It is an extremely leaky abstraction. This is not a theoretical possibility, I stumbled on the issue 15 minutes into my foray into asyncio (turns out that jupyter notebooks use asyncio internally). There are ways around that (spawn a separate thread with a dedicated event loop, then block), or monkey patch asyncio, but they are all ugly.
- Gibbon1 1y agoI do something like that with event driven firmware. There is an allocator as part of the context. And the idea that the function is executing under some context seems fine to me.
- laserbeam 1y ago> If anything, it would make sense to me to have IO contain an allocator too. Allocation is a kind of IO too. Io in zig is for “things that can block execution”. Things that could semantically cause a yield of any kind. Allocation is not one of those things. Also, it’s perfectly reasonable and sometimes desireable to have 13 different allocators in your program at once. Short lived ones, long lived ones, temporary allocations, super specific allocators to optimize some areas of your game… There are fewer reasons to want 2 different strategies to handle concurrency at the same time in your program as they could end up deadlocking on each other. Sure, you may want one in debug builds, another in release, another when running tests, but there are much fewer usecases of them running side by side.
- chrisohara 1y ago> Io in zig is for “things that can block execution”. Things that could semantically cause a yield of any kind. Allocation is not one of those things. The allocator may yield to the OS when requesting or releasing memory (e.g. sbrk, mmap, munmap)?
- messe 1y agoI don't find that a particularly compelling argument in this case, because so can accessing any memory address if it's not currently swapped in.
- deleted 1y ago[deleted]
- laserbeam 1y agoYielding in this context means to a different “thread” in your context, not the OS. If you want to express “this is a point where the program can do something else” it is a yield. If you block and can’t switch to something else… it is not. So if you’re using an API like mmap like that you should think of it as IO (I don’t think you can, but am not sure).
- throwawaymaths 1y ago
- pharrington 1y agoStockholm syndrome? Many years ago, I was specifically wanting a programming language where I could specify an allocator as a parameter! That's one of Zig's selling points.