> > When using an Io.Threaded instance, the async() function doesn't actually do anything asynchronously — it just runs the provided function right away.
> [...]
Well, yeah, but even if you spin up a thread to run "the provided function right away" it still will only be for some value of "right away" that is not instantaneous. Creating a thread and getting it up and running is often an asynchronous operation -- it doesn't have to be, in that the OS can always simply transfer the caller's time quantum, on-CPU state, and priority to the new thread, taking the caller off the CPU if need be. APIs like POSIX just do not make that part of their semantics. Even if they did then the caller would be waiting to get back on CPU, so thread creation is fundamentally an async operation.
> [...]
Well, yeah, but even if you spin up a thread to run "the provided function right away" it still will only be for some value of "right away" that is not instantaneous. Creating a thread and getting it up and running is often an asynchronous operation -- it doesn't have to be, in that the OS can always simply transfer the caller's time quantum, on-CPU state, and priority to the new thread, taking the caller off the CPU if need be. APIs like POSIX just do not make that part of their semantics. Even if they did then the caller would be waiting to get back on CPU, so thread creation is fundamentally an async operation.