问题
It's possible to write parallel code in Elm? Elm is pure functional, so no locking is needed. Of course, I can use Javascript FFI, spawn workers here and do it on my own. But, I want more user friendly "way" of doing this.
回答1:
Short answer
No, not currently. But the next release (0.15) release will have new ways to handle effects inside Elm so you will need to use ports + JavaScript code less. So there may well be a way to spawn workers inside Elm in the next version.
More background
If you're feeling adventurous, try reading the published paper on Elm (or the longer original thesis), which shows that the original flavour of FRP that Elm uses is well suited for fine-grained concurrency. There is also an async construct which can potentially make part of the program run separately in a more coarse-grained manner. That might be support with OS-level threads (like JS Webworkers) and parallelism.
There have been earlier experiments with Webworkers. There is certainly an interest in concurrency within the community, but JavaScript doesn't offer (m)any great options for concurrency.
For reading tips on the paper, here's post of mine from the elm-discuss mailing list:
If you want to know more about signals and opt-in async, I suggest you try Evan's PLDI paper on Elm. Read from the introduction (1) up to building GUIs (4). You can skip the type system (3.2) and functional evaluation (3.3.1), that may save you some time. Most in and after building GUIs (4) is probably stuff you know already. Figure 8 is probably the best overview of what the async keyword does (note that the async keyword is not implemented in the current Elm compiler).
来源：https://stackoverflow.com/questions/29181960/is-there-parallelism-in-elm