Scala Days in Berlin 2014


Around mid of June 2014 I have been visiting the Scala Days in Berlin. Like usual these events contain a lot of speeches, which were distributed in four tracks, apart from the key notes. The event location was a cinama, like the Devoxx in Antwerp, but this time one that has been transformed to something else many years ago, but good projectors were available. Major topics where issues about compiler construction which is a hard task, but looked at with the right functional perspective it can be derived from the simple task of writing an interpreter. This helps understanding language constructs in Scala, but the idea was applied to many other areas as well, for example for compiling and optimizing SQL queries and for analyzing source code.

Another major topic was „streams“, which can be useful for web services. Other than traditional web services which usually receive the whole request before starting to process it, concepts where discussed for dealing with large requests whose size is painful or impossible to keep at once in memory or who are even unlimited in size. These can also be applied to websockets. This demands processing data as soon as useful parts have arrived.

Another minor, but very interesting topic was development of Android apps with Scala. The commonly known approach is off course Scaloid, but an alternative, Macroid, was presented. It looked quite promising, because it allows to write nice Android apps with less code. A major worry is that scala apps consume too much memory due to their additional libraries. Because Scala uses its own libraries on top of the usual preinstalled Java libraries which are about 5 MB in size, this can easily anihilate the attractiveness of Scala for modern smart phone development, unless we assume rooted devices which have the Scala libs preinstalled. But that would seriously limit the scope of the app. This is not as bad as it sounds, because the build process contains one step in which unnecessary classes are removed, so that we only install what is really needed. When going as crazy as running Akka on the cell phone it becomes quite a challenge to configure this step because Akka uses a lot of reflection and so all these reflective entry points need to be configured, leaving a wide door open for bugs that occur at runtime when some class is not found.

API design was another interesting talk. Many ideas were quite similar to what I have heard in a API design traing for the Perl programming language by Damian Conway a couple of years ago, but off course there are many interesting Scala specific aspects to the topic. It is surprisingly hard to obtain binary compatibility of classes and this even forces to ugly compromises. So always recompiling everything looks tempting, but is not always reasonable. So ugly compromises remain part of our world, even when we are working with Scala.

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