Comfy Cats Effect room. Ask questions. Rant about config file formats. Be nice!
it's mostly a matter of time/resources
If you don't know enough of those principles from somewhere else then the docs confuse you
note that when the docs are just about general principles, people struggle with lack of practical how-tos. You need both ideally, and that's very time consuming
I've been using talks for the foundational stuff as it takes less time
I think at the very minimum we should have a page for the relevant talks, and then I encourage everyone to help us out with the docs :)
also, translate the links on @SystemFw's pages to docs
monix and fs2 both have that
they aren't a replacement for docs but they help
something something 4 types of documentation
tutorials, how-to guides, technical reference and explanation
Beginner question: How do I create
ContextShift[IO] without having to mixin IOApp? I'm working on introducing cats-effect into an Akka codebase and would like to use specific execution contexts to create different ContextShift[IO]. It seems IOContextShift is there but it's part of cats.effect.internals package
Is there a pattern for doing something like this:
type Thingy
def x[F[_]: Concurrent]: Resource[F, MVar[F, Thingy]] =
for {
sem <- Resource.liftF(Semaphore[F](1L))
mvar <- Resource.liftF(MVar.empty[F, Thingy])
fiber <- // construct a fiber that uses the semaphore and mvar and cancels when the resource is closed
} yield mvar
I maybe don't need the semaphore, actually. but I do want the mvar to be updated periodically and safely, until the resource is closed.
yeah, the mvar is enough that I don't need semaphore, when I started this I wasn't using an mvar...
The
fiber would be doing something like Stream.repeatEval(update(mvar)).metered(5.minutes)
but will they write to it as well? or it's just the update that does that?
Nobody else will update it
do you have an initial "default" value that you can give to
Thingy? if you do, then hold will fit your use case perfectly. If you don't, you can use most of the same tools that are under hold (concurrently mostly) and then compile.resource to have a Resource
I also realized that
MVar isn't quite right, because we're not waiting for someone to take a value out.
This is really just a way to monitor some external condition and compute a value when that condition changes
Thanks!