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functional-streams-for-scala/fs2

Compositional, streaming I/O library for Scala

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Jan 31 2019 04:19

404- forked
404-/fs2
Jan 31 2019 03:01

SethTisue commented #1232
Jan 30 2019 17:22

404- starred functional-streams-for-scala/fs2
Jan 30 2019 13:45

pjhampton starred functional-streams-for-scala/fs2
Jan 30 2019 10:48

pchlupacek commented #1406
Jan 30 2019 10:47

pchlupacek commented #1406
Jan 30 2019 10:39

pchlupacek commented #1407
Jan 30 2019 09:58

lJoublanc commented #870
Jan 30 2019 09:42

vladimir-popov commented #1407
Jan 30 2019 08:10

vladimir-popov closed #1407
Jan 30 2019 08:10

vladimir-popov commented #1407
Jan 29 2019 19:20

SystemFw commented #1407
Jan 29 2019 19:20

SystemFw commented #1407
Jan 29 2019 18:57

SystemFw commented #1406
Jan 29 2019 17:47

pchlupacek commented #1406
Jan 29 2019 17:42

pchlupacek commented #1406
Jan 29 2019 17:39

pchlupacek commented #1407
Jan 29 2019 17:39

vladimir-popov edited #1407
Jan 29 2019 17:38

vladimir-popov commented #1406
Jan 29 2019 17:37

pchlupacek commented #1406

Michael Pilquist

@mpilquist

We need compile to work with SyncIO

So that might be good reason for MonadCancel?

Daniel Spiewak

@djspiewak

hmm

so SyncIO doesn't have cancelation actually

it could; self-cancelation isn't that crazy

if you need compile to work with SyncIO, then yeah, MonadCancel is the only option

Michael Pilquist

@mpilquist

Either that or we have come internal adhoc thing that does attempt.flatmap on SyncIO

Daniel Spiewak

@djspiewak

…which is what @SystemFw did for Resource

so that's technically not outside the realm of sanity

I'm pretty tempted to do MonadCancel tbh

when one person builds an internal ad hoc thing, you ignore it

when two people build the same internal ad hoc thing, you consider the possibility that you're missing something

(ignoring for the moment the fact that Resource and Stream are isomorphic up to this particular need)

Michael Pilquist

@mpilquist

yep

Daniel Spiewak

@djspiewak

k, I'm going to risk the wrath of Fabio and give this a shot

Fabio Labella

@SystemFw

if you need compile to work with SyncIO, then yeah, MonadCancel is the only option

can it not take Resource.Bracket (the internal thing, fyi)

and note that it's not reuse for the sake of it because fs2-next uses compile.resource as the main loop anyway

the reason I prefer that over MonadCancel is that the actual use case is this: "if we allow cancelation, we need a Concurrent to express safety. If we don't, we need a MonadError for attempt.flatMap"

Fabio Labella

@SystemFw

and Resource.Bracket is just a lame OrElse to describe the above

MonadCancel says instead "because we need to support resourceful sync types, we shove (emphasis mine :P) (self-)cancelation into them, so we can talk about this uniformly"

Michael Pilquist

@mpilquist

Oh it may be able to

I guess that’s another reason to wait for Resource to land before getting going

Daniel Spiewak

@djspiewak

MonadCancel says instead "because we need to support resourceful sync types, we shove (emphasis mine :P) (self-)cancelation into them, so we can talk about this uniformly"

I mean, isn't that better than perpetuating an ad hoc typeclass that's just characterizing two broadly-unrelated things? :-)

Sam Desborough

@desbo

Hi all. Are there any examples of fs2 being used for streaming analytics / event aggregation? e.g. processing pageview events to build average number of views over a rolling window, etc. Or is this kind of thing outside of scope?

Adam Rosien

@arosien

@desbo it's a very common use case, for sure. there are a number of built-in methods that do that with one or two functions

Sam Desborough

@desbo

@arosien thanks, which ones are those? I'm currently finding myself using scan with a Map, to allow grouping by a particular ID, but would be interested to know about different approaches

Adam Rosien

@arosien

mapAccumulate is very common

(i'm just a beginner, but have seen many questions like this in this gitter channel)

Paul Snively

@paul-snively

@desbo: fs2 and Algebird are two great tastes that taste great together.

Calvin Lee Fernandes

@calvinlfer

Hey all, is it possible to interface with an Akka Persistence Query from FS2, I’m guessing I would have to use streamz to do this?

Paul Snively

@paul-snively

@calvinlfer: Akka Persistence Query is based on Akka Streams, so please see the fs2 Reactive Streams module: https://fs2.io/guide.html#reactive-streams

Calvin Lee Fernandes

@calvinlfer

Thanks @paul-snively i will take a look, I know Martin and @Daenyth have worked on a higher level api. Essentially, I need to interop with an Akka Streams Source

which i guess is a reactive streams Publisher

Yep seems to be Akka Streams Source = Publisher and Sink = Subscriber in the usual case. Cool, i should be able to use the reactive streams module directlyQ

thanks!

Paul Snively

@paul-snively

You bet!

Jens Grassel

@jan0sch

Hi, is there a recommend way from Stream[F, F[A]] to Stream[F, A]?

Erlend Hamnaberg

@hamnis

evalMap

Jens Grassel

@jan0sch

Thank you.

Gavin Bisesi

@Daenyth

@calvinlfer Look at streamz-converter, it offers akka-streams<->fs2 bindings

Christopher Davenport

@ChristopherDavenport

Is there any queue which allows you to offer batches that will be dequeued together? Or do I need to make the queue of Chunks in order to have that behavor?

Michael Pilquist

@mpilquist

Latter

Christopher Davenport

@ChristopherDavenport

Most efficient Chunk[Chunk[A]] => Chunk[A]?

I'm hoping .flatten

Adam Rosien

@arosien

"chunk-chunk-a-chunk"

Christopher Davenport

@ChristopherDavenport

Well I need to make sure some elements are actually sent as a unit.

But I still want to be able to enqueue multiple.

Michael Pilquist

@mpilquist

Chunk.concat