[rabito]

It was the runtime required to actually run the Futures.

Rust's Futures allow for easy chaining, whereas I only implemented a simple callback that runs on completion, but it doesn't allow one to get at the computed value directly. I simply send a "check for updates" event there. Instead the value gets stored in a Mutex and has to be pulled out of that explicitly, although it can stay in the "Async" type, just that it gets stored directly in the struct after it's pulled out of the Mutex. The advantage is you don't have to pay for the locking all the time and the value can stay where it is, so you don't need to juggle it around. You can see it here: https://github.com/rabite0/hunter/blob/master/src/preview.rs...

I started working on an improved version that actually allows for a callback with a reference to the value upon completion and also a callback that moves the value out, but I haven't finished that yet and after seeing this I might not ever, but I probably will, since it's definitely educative.

[steveklabnik]

To be clear, it's "a" runtime, not the runtime. It's the most popular one, but there's others as well, and some focus on embedded and binary size.

[rabito]

Sorry if that wasn't clear, it's been a rather long time since I checked on the Future story. There seem to be more options now than when I looked into it. When I did my research over half a year ago tokio seemed to be the only option. Glad to see that's not the case any more.

[steveklabnik]

It’s all good! To elaborate a bit, there’s a trait, Executor, that people can implement to build these kinds of things. This stuff, along with the final version of Futures, stabilized a few days ago. But it’s been baking a while.