Marcin bloguje

Scalar Conf 2016

Scalar Conf 2016

Polin museum - interior

This small conference had its third installment in ([Polin - Museum of the History of Polish Jews]. Organizing Scala conference isn’t that obvious and having that kind of attention is really great - all the foreign speakers, etc.

Here is a quick recap of presentations I’ve attended.

Having a cake … - by Paweł Szulc

A keynote about typeclasses. I’ve read the slides before the presentation -and they are available here, so it wasn’t new to me. But I’d strongly recommend to watch this talk.

Also, there is another nice talk by Paweł: Category theory is absolute general nonsense! This talk is in Polish only.

EFF Monad - by Eric Torreborre

Different way of monadic composition, implemented in a separate library: eff-cats (there is also scalaz alternative). Technically it was a bit over my head, but after experimenting with the concept at home it seems interesting.

I liked that Eric, being Zalando employee, developed that for their internal usage. Also the beauty of easily constructing different technological stacks with consistent API is very tempting.

Interesting things used/mentioned were:

Incremental compiler - by Krzysztof Romanowski

Deep dive into scalac incremental compiler implementation. While the presentation itself, the way it was presented, was very nice, I didn’t particularly enjoy the topic. It seemed more appropriate for tools’ developers.

Akka cluster with Etcd - by Maciej Biłas

This one looked promising. Joining multiple exciting technologies seems often that way. Unfortunately it was rather tech preview of Kubernetes app setup rather than Scala presentation.

I’m a bit disappointed, because looking through the sources of the project akka-cluster-etcd there are lots of things to describe. Kubernetes not being one of them ;-)

Shapeless? Easy! - by Valentin Kasas

Well, that was a clear introduction to shapeless. Till this presentation I’ve treated shapeless as only some vague thingy you use when writing libraries. Valentin proved otherwise.

He gave a clear and consistent tutorial on the basics of shapeless and its potential use in some example applications. He created a simple diff tool. Not that useful in real life application, but definitely helped make a point.

Will look into real life examples in near future.

Fun fact: The speaker had his presentation in REPLesent, a sbt plugin for presentations - and performed most of the slide-jumping-fu with just one hand, other held in his pocket :D Looked quite hilarious.

Valentin also mentioned shapeless’ typeclass derivation - this actually looks nice! Have a look at this question

Cool Toolz in the Scalaz and Cats Toolboxes - by Jan Pustelnik

Functional Design Patterns - enjoyable talk. With a bit of theoretical background, lots of useful use-cases. The talk was about cats and scalaz - both being very similar, and patterns they contain.

Key points being:

  • Functor pattern for abstracting Big Data computations, to achieve easier testability
  • composing functors - |@| scream operator - also know (officially) as Applicative Builder
  • Applicative - a list of computation into a computation of lists, list traversal
  • Applicative pattern for reading config

There is this nice video called “A purely functional approach to building large applications”. Go see it.


To conclude - the conference was really great. Both the talks and social side of the event were enjoyable. I’ve been blown away by the great architecture of the museum itself. Been there a couple times and enjoyed all of them.

The much needed change would be to bring more tracks, because sometimes topics were too specific and I’d gladly change lecture to some other.

As for the usual conference merch, there were no bags with leaflets and pens etc. It came as a surprise to me, but I also really liked it. People infact throw away most of the contents from such bags. Also, no t-shirt as a default - great idea! If you like it - just buy one, otherwise don’t bother.

Overall - great job Softwaremill! Keep up the good work!.