Rob Stewart
robstewartuk.bsky.social
Rob Stewart
@robstewartuk.bsky.social
Associate Professor at Heriot-Watt University. Accelerating functional languages and AI in software and hardware.

https://www.macs.hw.ac.uk/~rs46/
Supported by our EPSRC HAFLANG project.

haflang.github.io
HAFLANG - Hardware Acceleration of Functional Languages
haflang.github.io
July 3, 2025 at 3:09 PM
The final post-reviewed paper will be published by Springer in a few months.

The work is supported by the EPSRC HAFLANG project.

haflang.github.io
HAFLANG - Hardware Acceleration of Functional Languages
haflang.github.io
May 7, 2025 at 2:08 PM
Structured combinators are hardware-friendly encodings that more directly represent user functions compared to fine-grained SKI combinators, meaning generated programs are shorter. Our compiler supports Haskell 2010, and employs code-gen strategies to support full laziness and minimise program size.
May 7, 2025 at 2:08 PM
A list of more architectures would be great, I would happily add them to the timeline. Thanks for your interest.
April 2, 2025 at 10:07 AM
If you provide me with a list of related computer architectures that I've missed entirely from this timeline, I would be very grateful to receive this to update the timeline.
March 29, 2025 at 9:13 PM
And Gyula Magó's cellular's processor architecture here:

haflang.github.io/history#even...
HAFLANG - A History of Functional Hardware
haflang.github.io
March 29, 2025 at 9:13 PM
I mention Keller's (Utah) LISP machine here:

haflang.github.io/history#even...
HAFLANG - A History of Functional Hardware
haflang.github.io
March 29, 2025 at 9:13 PM
As for a Japanese machine, I very briefly mention the Evlis machine here, though you may have a different machine in mind:

haflang.github.io/history#even...
HAFLANG - A History of Functional Hardware
haflang.github.io
March 29, 2025 at 9:13 PM
And the Knight Machine at MIT machine that supported LISP in 1973, but perhaps that's a different MIT machine to the one you had in mind?

haflang.github.io/history#even...
HAFLANG - A History of Functional Hardware
haflang.github.io
March 29, 2025 at 9:13 PM
I completely agree about how important dataflow architectures were in the 1980s. I (briefly) mention the Manchester dataflow machine in the timeline:

haflang.github.io/history#even...
HAFLANG - A History of Functional Hardware
haflang.github.io
March 29, 2025 at 9:13 PM
Tiny suggestion - I'm unsure whether the 1st edition included an example of recursive Eval monad parallelism. Performance-wise, `runEval` is free, recursive calls to it doesn't have overhead. See the attached example. Apologies if recursive `runEval` calls is discussed, I must've missed it.
March 29, 2025 at 8:19 PM
Which is to ask: could a 2nd edition of the book be as clear as saying: if you're not in the habit of representing your computations as lazy data structures and you don't wish to familiarise yourself with evaluation strategies, then use the simpler Par monad API?
March 29, 2025 at 8:00 PM
When I advocate for the Eval monad in lectures, my analogy is it's parallel *breadth-first* search. E.g. the sudoku solver in your book, you want to eat away at lots of possible solutions rather than going down the rabbit hole of one: if you can fully embrace laziness, the Eval monad is for you.
March 29, 2025 at 7:50 PM
Any more reflections you have about Eval vs Par monads would be great. I still teach rpar/rseq, but I understand that @nishiorain.bsky.social taught using the Par monad. Could like-for-like code examples and their performance be given to demonstrate these pros/cons:

www.oreilly.com/library/view...
Parallel and Concurrent Programming in Haskell
Chapter 4. Dataflow Parallelism: The Par Monad In the previous two chapters, we looked at the Eval monad and Strategies, which work in conjunction with lazy evaluation to express parallelism. … - Sel...
www.oreilly.com
March 29, 2025 at 7:43 PM
Perhaps expanding on your December 2018 views about distributed-process on the parallel-haskell mailing list would be offer a retrospective insight about that library.

groups.google.com/g/parallel-h...
Cloud Haskell, closures, and statics
groups.google.com
March 29, 2025 at 7:28 PM
Today I added a slide about the collapse of the LISP machine market around 1987.

haflang.github.io/history.html...
HAFLANG - A History of Functional Hardware
haflang.github.io
March 29, 2025 at 10:44 AM
Laura Lisabeth
lauralisabeth.academia.edu
March 26, 2025 at 12:29 PM