Trends in Functional Programming

Abstract

This volume contains revised versions of selected papers that were presented at the 26th International Symposium on Trends in Functional Programming (TFP 2025), held at the University of Oxford from 14th to 16th January, 2025. TFP was co-located with the 14th International Workshop on Trends in Functional Programming in Education (TFPIE 2025), which took place on 13th January.

TFP is an international forum for researchers with interests in all aspects of functional programming, taking a broad view of current and future trends in this area. It aspires to be a lively environment for presenting the latest research results and other contributions. TFP reviewing is a two-phase, single-blind process where authors may either submit a full paper for review before the symposium, or submit an extended abstract before the symposium, followed by a full paper afterwards incorporating feedback from both the pre-symposium reviews and the presentations. Each paper receives at least three reviews per round. One paper over which I had a conflict of interest was handled separately by the Symposium Chair, Jason Hemann.

This year we received 35 submissions in total. Of these, 28 were presented at the symposium, along with three keynote talks: Things We Never Told Anyone about Functional Programming, by Mike Sperber from Active Group; Literate Programming and Cultural Practice, by Graham Nelson from St Anne's College, Oxford; and A Verified Foreign Function Interface Between Coq and C, by Kathrin Stark from Heriot-Watt University.

After the post-symposium review phase, revised versions of 20 papers were selected for inclusion in these proceedings. The final selections spanned a wide variety of topics including semantics, design, implementation, teaching, and programming. In addition to the 20 submitted papers, I am delighted to be able to include papers from Mike Sperber's and Graham Nelson's keynote talks.

By tradition, TFP offers two prizes. The John McCarthy Prize for the best paper overall was awarded to Matthew Pickering, Rodrigo Mesquita, and Adam Gundry for the paper Explicit Level Imports. And the David Turner Prize for the best student paper was awarded to Ellis Kesterton and Edwin Brady for the paper Heapless Functional Programming.

All of this was only possible thanks to the hard work of the authors, the insightful contributions of the Programme Committee members, the thoughtful advice from the TFP Steering Committee, and the generous support of our sponsors. Funding and organizational support for the event were provided by The Research Institute on Verified Trustworthy Software Systems (VeTSS) and Epic Games. Sincere thanks to everyone for making this year’s symposium a success.