4 ms·

You can't evaluate a future in normal rust as there's no default executor, you need to pull in some library to even make blocking calls to async functions. IMO

• zanellato19 3y ago
  You can also make your own executor. That's exactly how it was intended.
• weinzierl 3y ago
  It's a bit strange indeed. On the other hand you can't allocate either if you don't have an allocator. The difference is just that the allocator is opt-out while the reactor and executor are opt-in with no formal default.
• jarjoura 3y ago
  It's the same in C++. The compiler and language design came first and then the library (aka executor) part comes next. Rust has basically 2 executor libraries, tokio and async-std. It seems to me like tokio is solidifying as the executor of choice and it's only a matter of time before that design is baked into the std library.
  • menaerus 3y ago
    In C++ there is a default executor that is part of the standard library and has been so since C++11, e.g. no external library is needed - std::async. std::async is mostly "good enough" for ordinary cases where you only want to fire-and-forget and have no control over the underlying dispatching and scheduling algorithms. If you want something tweaked towards your use-case, and hence actual high-performance executor library, std::async is not gonna cut it. And that's where the "C++ executors" proposal come in.
    • BatmanAoD 3y ago
      That's...not precisely true. The C++ standard doesn't specify how std::async works, and for a while GCC just ran the operation sequentially, and later both GCC and Clang launched new OS threads by default. https://stackoverflow.com/q/10059239/1858225 https://stackoverflow.com/q/10059239/1858225