Raoul-Gabriel Urma has worked as a software engineer for Oracle's Java Platform Group, Google's Python team, Ebay, and Goldman Sachs as well as for several startup projects. He's currently completing a PhD in Computer Science at the University of Cambridge and is a regular speaker and instructor.
Mario Fusco is a senior software engineer at Red Hat working on Drools, the JBoss rule engine. He created the open source library lambdaj, an internal Java DSL for manipulating collections in a functional way.