79: Peter Thiemann

In this Haskell Interlude, we sat down with Tom Schrijvers, the head of the Functional Programming team at KU Leuven. He has been a prolific contributor to the foundations of Haskell, with many papers pushing the boundaries of the Haskell type system, programming with effects, and applications of functional programming.Our conversation was a whirlwind tour through Tom's long and wide publication history, with lots of tangents and ideas about functional programming, logic programming, constraints, DSLs, composition, program calculation, and other great stuff.

For the new Haskell Interlude, we sat down with Edward Kmett. Ed is the Founder and Chief Scientist of Positron AI. More importantly, he's a legend in the Haskell community for authoring many, many popular Haskell packages, first and foremost lens - and generally turning up the abstraction level to 11. We talk about design principles for Haskell libraries, category theory, cache-oblivious algorithms and his current work involving Haskell, C++, and FPGAs. Ed talks fast, so strap in!

In this episode, we sat down with Michael Hanus. Michael is a professor at the University of Kiel and is one of the founders of functional logic programming, the combination of logic and functional programming in a single formalism. Michael is also the creator of Curry, a functional-logic language that resembles Haskell, so you can dive right in if you're familiar with Haskell. Naturally, we talked about what functional logic programming is, how it improves over plain functional programming, and the challenges of semantics and implementation. We learned a lot - enjoy!Episode links and transcript

In today’s episode, we’re joined by Brent Yorgey, Associate Professor of Computer Science at Hendrix College and the creator, among other things, of the Diagrams vector graphics library and Swarm, a 2D programming and resource gathering game. We talk about teaching, domain specific languages, and competitive coding.Episode links and transcript

In this episode of the Haskell Interlude, we are joined by Sylvain Henry, one of the all-time top contributors to GHC. He tells us about his work on GHC, the bignum library, modularization, and the secret to becoming a top contributor!

This is the first part of a miniseries on this year’s Symposium on Principles of Programming Languages, a.k.a. POPL 2026, hosted by Jessica Foster.In this episode we talk about: symbolic execution monads, what a lazy linear core in Haskell might have in common with Rust, hyperfunctions, the hallway track, and how to deal with rejection.

We talked to Fraser Tweedale. Fraser works at Red Hat, and is on the Haskell Security Response Team. We talked about security in the context of Haskell, both technical and organizational issues, and also the political issues involved. Fraser's work is both really important and not well-known in the Haskell ecosystem, so it was high time for him to come on the show.

Mike and Andres sat down with Torsten Grust, who is a professor of DB systems at the University of Tübingen. Even though Torsten loves SQL, he's used functional programming and Haskell to inform his work on query language design and compilation. We talked about the best way to program databases, how to bridge the gap between regular programming languages and databases, and compiling just about everything to SQL. 

This is the first part of a miniseries on this year’s Symposium on Principles of Programming Languages, a.k.a. POPL 2026, hosted by Jessica Foster.In this episode, we talk about: undergrad funding and participation, the behind the scenes of AV, choreographic programming, quantum languages, conference catering, and the joy of theory. And at one point, you’ll even hear us get kicked out the venue mid interview. Enjoy!

Peter is a professor at the University of Freiburg, and he was doing functional programming right when Haskell got started. So naturally we asked him about the early days of Haskell, and how from the start Peter pushed the envelope on what you could do with the type system and specifically with the type classes, from early web programming to program generation to session types. Come with us on a trip down memory lane!