https://billo.systems/articles/ Careful engineering at serious scale. Sun, 20 Sep 2026 12:00:00 -0600 https://billo.systems/articles/2026/09/from-a-local-chat-client-to-a-cognitive-environment/ https://billo.systems/articles/2026/09/from-a-local-chat-client-to-a-cognitive-environment/ Sun, 20 Sep 2026 12:00:00 -0600 Duncan McGreggor airustknowledge-graphsoftware-engineering A locally owned place for conversation, memory, knowledge and planning—and how a question about a Mac chat client brought years of separate work into the same design. https://billo.systems/articles/2026/09/ai-engineering-knowledge-library/ https://billo.systems/articles/2026/09/ai-engineering-knowledge-library/ Sat, 05 Sep 2026 12:00:00 -0600 Duncan McGreggor airustsoftware-engineering Reworking our engineering framework into composable skills and focused guides, then comparing it with 0.4.1 through real planning, Rust implementation and code audits. 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 How process dependencies, restart policies and state reconstruction determine whether an Erlang service can recover from a crash. 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-sidebar-neural-representations/ https://billo.systems/articles/2026/05/ai-recap-sidebar-neural-representations/ Thu, 21 May 2026 09:00:00 -0600 Duncan McGreggor aineural-networksphilosophy From authored ontologies to learned features: how we investigate neural representations, what their geometry can tell us, and where observation gives way to interpretation. https://billo.systems/articles/2026/05/ai-recap-sidebar-soft-thresholds-bargain/ https://billo.systems/articles/2026/05/ai-recap-sidebar-soft-thresholds-bargain/ Wed, 20 May 2026 09:00:00 -0600 Duncan McGreggor aineural-networksmathematics Why sigmoid units made gradient-based training practical, how saturation complicates learning in deep networks, and how later methods address gradient propagation. 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 Returning to neural networks after two decades: the training difficulties, competing methods and continuing research that connect backpropagation to AlexNet. 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.