Added Task.parallel

[TheSeamau5]

Added simple implementation for Task.parallel. This function will run
a lists of tasks in parallel and will return a task that computes a
list of ThreadIDs.

Solves this issue: https://github.com/elm-lang/core/issues/223

As @johnpmayer pointed out here, further down the road, we may want to get an MVar implementation a la Haskell in Elm. This would give more fine grain control and allow communication between "threads". Currently, those ThreadID values are completely useless (aside from debugging) but they could be put to good use.

But, in the meantime, this is not a bad option and it's worth adding to the core library due to how common this use case is.

[evancz]

For the reasons, described in that thread here, I'd like to wait on a proper implementation of this. For now, people can spawn a bunch of stuff or make a library. I think adding the wrong semantics to a core library is not a good thing to do.

[evancz]

For the reasons, described in that thread here, I'd like to wait on a proper implementation of this. For now, people can spawn a bunch of stuff or make a library. I think adding the wrong semantics to a core library is not a good thing to do.

[TheSeamau5]

Cool. Anyways, if people need this sort of thing, there's a library:
http://package.elm-lang.org/packages/TheSeamau5/elm-task-extra/2.0.0
It has parallel and optional and a few others.

[TheSeamau5]

Cool. Anyways, if people need this sort of thing, there's a library:
http://package.elm-lang.org/packages/TheSeamau5/elm-task-extra/2.0.0
It has parallel and optional and a few others.