Wren Dahl
Type theorist · independent · former Idris contributor · curator of The Reading Group
Lambda calculus is fun. It is also somehow proven correct. Both of these are true at the same time.
Areas of practice.
A non-exhaustive list of what Wren works on, has shipped, or has very strong opinions about.
Working on.
I hold a PhD in type theory from Edinburgh and contributed to Idris for a number of years before stepping back to teach independently. At Lattice I curate The Reading Group and run the Functional Foundations track.
I have spent more time than is strictly reasonable teaching the Y-combinator to people who came to a coding bootcamp expecting React. I have, on the whole, found this rewarding.
Functional Foundations is the eight-week track that everyone underestimates and almost no one regrets. We start with the untyped λ-calculus, work through System F, end with a small dependently-typed language. The exercises are short. The papers are not.
The Reading Group meets every Tuesday at seven. We read one paper a fortnight, slowly. The current track is the EWDs — Dijkstra's hand-written notes — and we are, predictably, behind schedule.
In the curriculum.
Recent writing & talks.
A small, current selection. The full list lives in the Lattice Journal archive.
Currently on the desk.
What Wren is reading or returning to. Many of these are assigned somewhere in the curriculum.
- 01Structure and Interpretation of Computer Programs · Abelson & Sussman1985
- 02Why Functional Programming Matters · Hughes1989
- 03Bidirectional Type Checking · Pierce & Turner2000
- 04Types and Programming Languages · Pierce2002
- 05Selected EWDs · Dijkstra1968 →
Reserve a seat in
Type Theory & Functional Foundations.
Wren's Type Theory course opens for Cohort XIII in January 2026. Eight weeks, remote, capped at twenty students. The Reading Group runs year-round and is open to alumni and applicants.
Begin your application