Playing with futures

During job interviews we often give Scala developers a simple design task: to model a binary tree. The simplest but…

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instanceof operator and Visitor pattern replacement in Java 8

I had a dream where instanceof operator and downcasting were no longer needed but without clumsiness and verbosity of visitor…

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Optional in Java 8 cheat sheet

java.util.Optional<T> in Java 8 is a poor cousin of scala.Option[T] and Data.Maybe in Haskell. But this doesn’t mean it’s not…

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Asynchronous retry pattern

When you have a piece of code that often fails and must be retried, this Java 7/8 library provides rich…

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Managing congested actors in Akka

There comes a time in an Akka application when an actor can longer handle increasing load. Since each actor can…

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Fake system clock pattern in Scala with implicit parameters

Fake system clock is a design pattern addressing testability issues of programs heavily relying on system time. If business logic…

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su and sudo in Spring Security applications

Long time ago I worked on a project that had a quite powerful feature. There were two roles: user and…

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Macro lifecycle in Clojure

If you still struggle to understand what are macros in Clojure and why are they so useful, I will guide…

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Clojure macros for beginners

This article will guide you step-by-step (or even character-by-character) through the process of writing macros in Clojure. I will focus…

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