Proceedings Ninth Workshop on Mathematically Structured Functional Programming

This volume contains the proceedings of the Ninth Workshop on Mathematically Structured Functional Programming (MSFP 2022). The meeting took place on the 2nd of April as a satellite of European Joint Conferences on Theory & Practice of Software (ETAPS 2022). The MSFP workshop highlights applications of mathematical structures to programming applications. We promote the use of category theory, type theory, and formal language semantics to the development of simple and reasonable programs. As the range of papers presented in this year's workshop shows, this continues to be a fruitful interface.