Alan is well-known for pioneering contributions to programming language theory and applications, covering both design and implementation. His work ranges from compilation and optimisation techniques, through semantics, static analysis, and type systems, to parallel, concurrent, and dataflow programming. He co-created the Norcroft C compiler with Arthur Norman, he co-authored the book Java 8 in Action: Lambdas, Streams, and Functional-Style Programming, and he co-founded the Raspberry Pi Foundation, a hugely successful initiative to develop programming skills and thinking for all ages.

In addition to his excellent research profile, Alan has been an inspiring teacher, mentor, and collaborator, always generous with encouragement and feedback. The impact and scope of his career is reflected in the breadth of topics in this volume, a fitting tribute to him.