The 14th ACM SIGPLAN International Conference on Functional Programming (ICFP) took place on August 31–September 2, 2009 in Edinburgh, Scotland; Andrew Tolmach chaired the program committee. Following the conference, the authors of selected papers were invited to submit extended versions for this special issue of JFP. After review and revision, four papers were accepted for inclusion in this volume. Each paper contains substantial new material beyond the original conference version. The papers are representative of the wide range of topics and methodology that characterize ICFP.