MicroHs, a tiny Haskell Compiler – Lennart Augustsson (Language Pioneer & Compiler Expert)

Lennart Augustsson presents MicroHs, a lightweight Haskell compiler that translates code into combinators executed by a portable C runtime.

In this engaging and technically rich talk, Lennart Augustsson presents his project microHs – an extremely lightweight Haskell compiler developed both as a fun experiment and a deep dive into functional programming. Augustsson, known for having written several Haskell compilers and for his award-winning entries in the International Obfuscated C Code Contest, demonstrates the installation, usage, and unique features of MicroHs live. He explains how the compiler translates Haskell code into combinators, which are then executed using a runtime system based in combinators written in C. The result is a tiny, portable binary – even suitable for microcontrollers. About Lennart Augustsson Lennart Augustsson is a longtime contributor to the field of programming languages, known especially for his early Haskell implementations and for designing the dependently-typed language Cayenne. He has worked at the intersection of theory and systems in both academic and industrial settings and continues to shape the way we think about functional programming today. Lennart Augustsson was introduced by Farhad Mehta. 🧠 Talk Highlights (Chapters): 00:00 · Introducing Lennart Augustsson 01:50 · What is microHs? A small Haskell compiler 03:22 · Live installation demo 05:14 · Interactive mode and math with complex numbers 06:37 · Compiling and running Haskell programs 08:10 · Comparing binary sizes: microHs vs. GHC 10:13 · Cross-compilation & WebAssembly support 14:02 · Why build another Haskell compiler? 16:12 · Combinator-based compilation (Turner-style) 17:02 · Running on bare metal and microcontrollers 19:54 · microHs vs. GHC: Speed and binary size 21:16 · Implemented language extensions 23:22 · Limitations: No Template Haskell, some concurrency 24:00 · microCabal: Building packages without full Cabal 26:00 · Compiler architecture overview 27:48 · Serialization and caching 30:00 · Church & Scott encoding of data types 33:15 · Overview of SKI combinators 36:02 · Optimization rules and combinator reduction 38:10 · Self-optimizing properties of combinators 40:14 · Specialization and dictionary elimination 44:23 · The C runtime and performance: ~3ns per reduction 46:22 · Garbage collection: bitmap-based strategy 49:28 · Compilation statistics: combinators, GC, runtime 51:19 · Serialization formats and portability 53:28 · Running microHs on microcontrollers (Morse demo) 54:10 · Community contributions & thanks 55:26 · Audience Q&A: Hardware execution, performance, IO, etc. With humor and deep technical insight, Augustsson shares his experience, including notes on Unicode support and community contributions. One particularly impressive demo: microHs running on a microcontroller, blinking in Morse code – of course written in Haskell. 🔧 A must-watch for anyone interested in compiler design, functional programming, or software minimalism! #Haskell #CompilerDesign #FunctionalProgramming