Julia Lawall is a research scientist at Inria-Paris. Previously, she was on the faculty at the University of Copenhagen. Her research covers the areas of programming languages, software engineering and systems, with a particular interest in improving the development of operating systems. Among her early work was contributions to the Schism partial evaluator for Scheme and the Tempo partial evaluator for C, developed in the group of Charles Consel at Inria-Rennes. She also contributed to the development of domain-specific languages for a variety of systems programming tasks. More recently, she has led the development of the Coccinelle program matching and transformation tool for C code, which has been used in of thousands of commits to the Linux kernel. In this talk, she will connect the dots between these research directions, showing how the work on partial evaluation and domain specific languages has led to the design decisions behind Coccinelle, and how those design decisions have led to the success of the tool in practice.