He has been using Scala for quite a while now, and is known as one of the founders of the Typelevel initiative which is dedicated to providing principled, type-driven Scala libraries in a friendly, welcoming environment. A frequent conference speaker and community representative at the Scala Center Advisory Board, he is active in the open source community, particularly in Scala. He also enjoys programming in and talking about Haskell, Prolog, and Rust.