Akka Best Practices

 Posted on August 18, 2016  |  3 minutes  |  Harry Laoulakos

Don’t share mutable state among actors Do not close on the sender Do not close over an actor’s context Do not use the scheduler with the Runnable trait Do not declare one actor within another. Never pass an actor’s this reference into Props Actors do not stop automatically when no longer referenced, every Actor that is created must also explicitly be destroyed. The only simplification is that stopping a parent Actor will also recursively stop all the child Actors that this parent has created. [Read More]

Free Monads

Resources on learning free monads

 Posted on August 10, 2016  |  2 minutes  |  Harry Laoulakos

Here are some resources about the free monad in scala . At some point I need to write summaries for each entry :) Blog posts Free Monads I had bookmarked this sometime ago and seems to be very to the point without a lot of theotitical analysis Free Monad - Cats Documentation by Pascal Voitot herding cats - Free monads by Eugene Yokota Deriving the Free Monad by Noel Welsh [Read More]

Shapeless: Introduction resources

Where to start if you want to learn shapeless

 Posted on July 27, 2016  |  3 minutes  |  Harry Laoulakos

Recently I decided to have a better look at shapeless, the generic programming library for scala. In the previous couple of years I had bookmarked several links and have recently read all of them . In this blog post I present the most useful ones for someone who want to be introduced to the library. The following blog posts are introductory to shapeless. Basically they are a smooth introduction to shapeless , something to warm up [Read More]

Shapeless : Computing deltas

A real life example

 Posted on July 26, 2016  |  5 minutes  |  Harry Laoulakos

This is the code and some personal notes from the Shapeless? - Easy! talk where Valentin Kasas explains in a great way an advanced example of a real life use case (with slides). Computing deltas Imagine we want to be able to determine what are the difference between two objects of the same type For example, we need to know what have changed in our DB since the last backup We need to be able to compute such deltas over a wide variety of classes, that are unrelated Of course, doing this by hand for each and every class is not an option Our diff representation [Read More]

Scala libraries

 Posted on July 10, 2016  |  15 minutes  |  Harry Laoulakos

Whenever I come I across a Scala library I take a note of it here. This collection is neither complete nor have I used all of these libraries. It is mainly used as a point of reference if I want to find some functionality implemented in a Scala library. Akka hseeberger/akka-sse Server Sent Events for Akka HTTP ktoso/akka-raft toy project implementing RAFT on top of Akka Cluster (not prod ready) [Read More]