

Type Theory Forall
Pedro Abreu
An accessible podcast about Type Theory, Programming Languages Research and related
topics.
topics.
Episodes
Mentioned books

May 14, 2025 • 2h 7min
#50 The Expression Problem, Functional Pearls, Program Calculation - Wouter Swierstra
Wouter Swierstra is a Math Bachelor’s from the University of Utrecht, has done his PhD with Thorsten Altenkirch at the University of Nottingham, did a post-doc at Chalmers, has experience in the industry working on facilitating the design of embedded system using FP and currently is a Professor at the University of Utrecht and co-host of the Haskell Interlude Podcast.
In this episode we talk about his trajectory into formal methods and functional programming. We talk about Datatypes a la Carte, the Expression Problem, Functional Pearls, Program Synthesis vs Program Calculation, and much more!
0:00 – Intro & Welcome
0:02:08 – Announcing the Type Theory Forall Merch Store!
1:12 – Early Influences: From Lenses to Logic
4:40 – Discovering Functional Programming in Utrecht
8:15 – On Monads, Papers, and Learning by Teaching
12:20 – What Makes a Paper ‘Beautiful’?
17:50 – PhD in Nottingham: Theory Meets Community
22:00 – Writing ‘Certified Programming with Dependent Types’
29:10 – Teaching Dependent Types: Challenges and Joys
34:00 – On Agda vs Coq: Philosophies and Use Cases
38:40 – Type-Driven Development in Practice
45:05 – The Power of Elegant Proofs
52:00 – Advice to Aspiring Researchers in Type Theory
1:03:00 – Beating C with Functional Programming
1:20:00 – Formal Verification and Loop Invariants
1:33:28 – Program Calculation vs Program Synthesis
1:39:00 – Formalizing Blockchain
2:01:38 – Final Thoughts
Links
Wouter Website
Haskell Interlude
Advanced FP Summer School
ttforall twitch
ttforall store
Discount code for 10% off: typetheory

10 snips
Mar 14, 2025 • 2h 24min
#49 Self-Education in PL - Ryan Brewer
Ryan Brewer, a self-taught programming language expert and creator of innovative projects like Saber VM, shares his journey from college dropout to blog writer, dedicated to making formal theory accessible. Joined by researcher Dan Plukin, they discuss the challenges and joys of self-education in programming, the intersection of ethics and technology, and their experiences with compilers. They emphasize the importance of passion in learning and critique traditional academic paths, while encouraging openness in the programming community.

Jan 21, 2025 • 2h 10min
#48 Bell Labs - David MacQueen
In this episode we continue with our conversation with David MacQueen, he is an Emeritus Professor from the University of Chicago, and has worked at Bell Labs for 20 years.
Bell Labs began as the research and development section of the American Telephone and Telegraph company, aka AT&T, which originally hold exclusive hold of the telephone patent. Once that expired in the 1800s they needed to develop new technology to prove that it was still the best company, and hence Bell Labs was born.
Over the course of the years this fascinating institution has registered more than 26 thousand patents, among of which we have the transistor, the laser, the solar cell and communication satellites. Over the course of the last 88 years they were awarded a jaw dropping amount of 10 Nobel prizes and 5 Turing awards.
In this interview David MacQueen shares with us how was it like to work in such an incredible institution during it’s golden age. He shares insights about the technology, the space, the people, the management style, and much more!
Links
David's Website
David's Github

Jan 7, 2025 • 2h 5min
#47 The History of LCF, ML and HOPE - David MacQueen
David MacQueen has worked at Bell Labs for around 20 years during it’s Golden Age. Professor at Chicago University for 23 years. He is one of the designers of SML, one of the fathers of HOPE the programming language that introduced the notion of Algebraic Datatypes.
So this interview was very special to me personally where I could get to hear all the stories about the dawn of Functional Programming as we know. And it is my great pleasure to have the honor to share it with you all.
Links
David's Website
David's Github
Luca Cardelli and the Early Evolution of ML
The History of SML
HOPE
SML Website
SML/NJ Website
SML/NJ Github
SML Family Website

Nov 29, 2024 • 1h 4min
#46 Realizability, BHK, CPS Translation, Dialectica - Pierre-Marie Pédrot
In this episode Pierre-Marie Pédrot, one of the main Coq/Rocq developers joins us to talk about Krivine, Kleene and Gödel Realizability Models, how it relates to the BHK interpretation and CPS Translations, and how it was all already part of Gödel's work in Dialectica!
If you enjoy the show please consider supporting us at our ko-fi: https://ko-fi.com/typetheoryforall
Links
Pierre-Marie's Website
Pierre-Marie's PhD Thesis (Very nice read)
BHK Interpretation
Type Theory Forall website
Type Theory Forall discord

Nov 24, 2024 • 1h 22min
#45 What is Type Theory and What Properties we Should Care About - Pierre-Marie Pédrot
In this episode Pierre-Marie Pédrot who is one of the main Coq/Rocq developers joins us to talk about what is Type Theory, what is Martin-Löf Type Theory, what are the properties we should care about in our type theory and why.
If you enjoy the show please consider supporting us at our ko-fi: https://ko-fi.com/typetheoryforall
Links
Pierre-Marie's Website
Type Theory Forall website
Type Theory Forall discord

6 snips
Nov 6, 2024 • 2h 14min
#44 Theorem Prover Foundations, Lean4Lean, Metamath - Mario Carneiro
Mario Carneiro is a postdoc at Chalmers University and the creator of Mathlib and Metamath0, focusing on theorem provers and formal verification. He discusses the evolution of the Lean proof assistant, tackling challenges in type theory and interoperability of proof systems. The conversation includes insights on the user experience in proof systems, the introduction of MetaMath Zero, and the importance of community collaboration in development. Carneiro also reflects on the complexities of proof assistants and the necessity of efficient theorem proving.

Sep 13, 2024 • 1h 2min
#43 PL in the Industry and Summer Schools - Patrick and Eric
In this episode Eric Bond and Patrick Lafontaine joins us to talk about the life in industry vs the life in academia. Eric is a PhD student at Michigan University under Max New, he works with some pretty cool esoteric cubical agda stuff. Before starting his PhD he has spent some time at the consultancy companies Two Six Technologies and 47 Degrees doing some cool functional programming and formal methods. Before that we were pals doing an internship at Galois, and even before that he finished his masters with Benjamin Delaware at Purdue, Patrick’s current advisor. Patrick has just returned from his internship at AWS in the automated reasoning team. So in this episode we talk about their research, their academic and industry experiences, how’s the industry looking like for opportunities in PL and all that.
If you enjoy the show please consider supporting us at our ko-fi: https://ko-fi.com/typetheoryforall

Aug 29, 2024 • 1h 53min
#42 Distributed Systems, Microservices, and Choreographies - Fabrizio Montesi
In this episode we talk with Fabrizio Montesi, a Full Professor at the University of South Denmark. He is one of the creators of the Jolie Programming Language, President of the Microservices Community and Author of the book 'Introduction to Choreographies'. In today’s episode we talk about the formal side of Distributed Sytems, session types, the calculi that model distributed systems, their type systems, their Curry-Howard correspondences, and all the main ideas around these concepts.
If you enjoy the show please consider supporting us at our ko-fi: https://ko-fi.com/typetheoryforall
Links
Fabrizio's Website
Fabrizio's Linkedin
Fabrizio's X / Twitter
Fabrizio's Mastodon
Fabrizio's Youtube
Jolie's Website

Aug 15, 2024 • 1h 41min
#41 The Value of PL (and) Education - Satnam Singh
Satnam Singh has got incredible experience in both academia and industry. He has worked in Google, Facebook, Microsoft, Microsoft Research, Xilinx, etc. He has been a lecturer in Glasgow, Birmingham and University of California for a couple of years. He has worked with many interesting tools such Coq, Haskell, Verilog, Tensorflow. These days he works at Groq, applying FP to design silicon for machine learning. In this episode we talk about the value of specification, the current state of academia, gaming the metrics, functional programming in hardware, bullying, among other things.
If you enjoy the show please consider supporting us at our ko-fi: https://ko-fi.com/typetheoryforall
Links
Personal Website
Satnam's X
Groq


