threading? (concurrent execution)

[-X-]

Does REBOL support concurrent execution ("threading")?, or how might such things apply in REBOL code?

[Gregg]

REBOL does not have any native multithreading capability, but you can do cooperative threading on your own if you need to. Rugby has a built-in engine for that, or you can roll your own pretty easily. It does take a slightly different development model though, just so you're aware (in case you're not already).

[Carl]

Yes, the current REBOL is single-threaded, but you can fire up as many REBOL processes as you want, just use the launch function to do that. (For example, every app in IOS is launched in this way.) You can use ports to communicate and sync between the processes.

In addition, as Gregg mentioned, REBOL has an internal method of handling wait events, called wait lists.  This is how ports and GUI events get processed while your main loop is in the WAIT function.

The plan for REBOL 3.0 is to add lightweight tasks. These are similar to threads, but with a less implicit sharing model (no shared variables by default).