https://billo.systems/articles/ Careful engineering at serious scale. Thu, 18 Jun 2026 09:00:00 -0600 https://billo.systems/articles/2026/06/supervision-trees/ https://billo.systems/articles/2026/06/supervision-trees/ Thu, 18 Jun 2026 09:00:00 -0600 Duncan McGreggor erlangotp Let-it-crash is not carelessness. It's a theory of where responsibility lives — enforced by the runtime rather than by anyone's good intentions. https://billo.systems/articles/2026/06/bringing-types-to-lfe/ https://billo.systems/articles/2026/06/bringing-types-to-lfe/ Sun, 14 Jun 2026 10:08:00 +0000 Duncan McGreggor lfetypestype-systemsgradual-typinglykngleamhaskellrustracketcoaltonclojure Why we started building a gradual type system for Lisp Flavoured Erlang — a tour through how Haskell, Go, Rust, Typed Racket, Coalton, and Typed Clojure each spell the same small idea, the ergonomic quibbles that pushed us, and the strategic moves we borrowed from Gleam. https://billo.systems/articles/2026/06/graph-theory-in-lfe-graffeo-erlang-knowledge/ https://billo.systems/articles/2026/06/graph-theory-in-lfe-graffeo-erlang-knowledge/ Sat, 06 Jun 2026 10:08:00 -0600 Duncan McGreggor graph-theoryerlangotpknowledge-graphdijkstramathematicslibraries A deep, hands-on tour of graph theory in LFE — built on a real corpus of 1,664 Erlang concept cards, driven by the graffeo library, and unfolded slowly enough to teach the mathematics underneath each query. https://billo.systems/articles/2026/06/lykn-a-lisp-born-from-lfe/ https://billo.systems/articles/2026/06/lykn-a-lisp-born-from-lfe/ Fri, 05 Jun 2026 18:00:00 -0600 Duncan McGreggor lfelyknlispjavascriptlanguagesrelease How fourteen years with Lisp Flavoured Erlang led to a new language — and how that language came home to power lfe.io. https://billo.systems/articles/2026/05/ai-recap-1-neural-networks-second-winter/ https://billo.systems/articles/2026/05/ai-recap-1-neural-networks-second-winter/ Tue, 19 May 2026 09:00:00 -0600 Duncan McGreggor aineural-networkshistory I left the field when neural networks were a failed research program. I came back to find they had won everything. Part 1 of a catch-up, two decades deep. https://billo.systems/articles/2026/05/nine-nines/ https://billo.systems/articles/2026/05/nine-nines/ Sat, 09 May 2026 09:00:00 -0600 Duncan McGreggor reliabilitydistributed-systems Every additional nine is one decimal point away and an order of magnitude harder. The question is never whether you can afford it, but who pays. https://billo.systems/articles/2026/04/vector-databases/ https://billo.systems/articles/2026/04/vector-databases/ Tue, 21 Apr 2026 09:00:00 -0600 Duncan McGreggor aiinfrastructure Strip the marketing and a vector store is an index that has made peace with being approximately right. That peace is the whole engineering problem. https://billo.systems/articles/2025/12/raft-in-anger/ https://billo.systems/articles/2025/12/raft-in-anger/ Mon, 15 Dec 2025 09:00:00 -0600 Duncan McGreggor consensusdistributed-systems The paper is elegant; production is not. Here is what leader election actually does when the network is having a genuinely bad day. https://billo.systems/articles/2015/01/translating-sicp-into-lfe/ https://billo.systems/articles/2015/01/translating-sicp-into-lfe/ Wed, 28 Jan 2015 21:12:00 -0600 Duncan McGreggor lfesicplispbooks The Wizard Book is getting an LFE edition — why I'm porting Abelson and Sussman across, a paragraph at a time, what has to change on the way (procedures, for one), and what must never change. https://billo.systems/articles/2014/12/scientific-python-on-the-beam/ https://billo.systems/articles/2014/12/scientific-python-on-the-beam/ Wed, 31 Dec 2014 22:00:00 -0600 Duncan McGreggor lfeerlangpythonscientific-computing The matplotlib book left me wondering how much of the scientific-Python world I could pull onto the Erlang VM. The answer became two projects, a discovery I didn't plan, and line charts drawn in the terminal. https://billo.systems/articles/2014/12/erlport-using-python-from-erlang-lfe/ https://billo.systems/articles/2014/12/erlport-using-python-from-erlang-lfe/ Wed, 03 Dec 2014 01:08:00 -0600 Duncan McGreggor howtoserlportpythoninteroplfelibraries A Quick Introduction to ErlPort via LFE https://billo.systems/articles/2014/11/mastering-matplotlib/ https://billo.systems/articles/2014/11/mastering-matplotlib/ Sun, 30 Nov 2014 00:33:00 -0600 Duncan McGreggor pythonmatplotlibdata-visualizationtechnical-writingscientific-computing A cold email, a move to the Midwest, and a month spent deciding that "mastering" means going down to the architecture — the layers, the event loops, the module graph itself. https://billo.systems/articles/2014/11/company-site-is-live/ https://billo.systems/articles/2014/11/company-site-is-live/ Mon, 17 Nov 2014 11:03:00 -0600 Duncan McGreggor announcementsdesigngraphicsweb Announcing the launch of the original Billo Systems company site — a note on the build, the tools that made it painless, and the drafts still to come.