Programming languages like Scala enable modular library-based extensions providing new high-level abstractions or even embedded domain-specific languages (DSLs). While the embedding of a DSL in a general-purpose host language enables reusing the compilers, debuggers, and IDEs of the host language, it also gives rise to a number of important challenges. For example, actors in Scala are concurrent processes that are multiplexed to run on a thread pool by default. As a result, standard stack-based debuggers are no longer effective. Over the last 10 years I have contributed to the design of several concurrency libraries for Scala powering the websites of companies like LinkedIn and The Guardian. In this talk I attempt to provide an overview of the challenges for tool support that high-level concurrency libraries pose.

Assistant Professor in the School of Computer Science and Communication at KTH Royal Institute of Technology, Sweden.