Seconds Since the Epoch
This is not at all news, but it comes up often enough that I think there should be a concise explanation of the problem. People, myself included, like to say that POSIX time, also known as Unix time, is the number of seconds since the Unix epoch, which was 1970-01-01 at 00:00:00. This is not true. Or rather, it isn’t true in the sense most people think. For example, it is presently 2024-12-25 at 18:54:53 UTC. The POSIX time is...
2 days ago
Threads Won't Take You South of Market
In June 2023, when Threads announced their plans to federate with other Fediverse instances, there was a good deal of debate around whether smaller instances should allow federation or block it pre-emptively. As one of the admins of woof.group, I wrote about some of the potential risks and rewards of federating with Threads. We decided to wait and see. In my queer and leather circles, Facebook and Instagram have been generally understood as hostile environments for over a decade. In...
26 days ago
Ecobee Settings for Heat Pumps with Resistive Aux Heat
I’m in the process of replacing a old radiator system with a centrally-ducted, air-source heat pump system with electric resistive backup heat. I’ve found that the default ecobee algorithm seems to behave surprisingly poorly for this system, and wanted to write up some of the settings that I’ve found yield better behavior. A disclaimer. I’m not an HVAC professional. I have two decades in software operations, a background in physics, and far too much experience inferring system dynamics from timeseries...
10 months ago
ClassNotFoundException: java.util.SequencedCollection
Recently I’ve had users of my libraries start reporting mysterious errors due to a missing reference to SequencedCollection, a Java interface added in JDK 21: Execution error (ClassNotFoundException) at jdk.internal.loader.BuiltinClassLoader/loadClass (BuiltinClassLoader.java:641). java.util.SequencedCollection Specifically, projects using Jepsen 0.3.5 started throwing this error due to Clojure’s built-in rrb_vector.clj, which is particularly vexing given that the class doesn’t reference SequencedCollection at all. It turns out that the Clojure compiler, when run on JDK 21 or later, will automatically insert references to this class...
10 months ago
How to Replace Your CPAP In Only 666 Days
This story is not practical advice. For me, it’s closing the book on an almost two-year saga. For you, I hope it’s an enjoyable bit of bureaucratic schadenfreude. For Anthem, I hope it’s the subject of a series of painful but transformative meetings. This is not an isolated event. I’ve had dozens of struggles with Anthem customer support, and they all go like this. If you’re looking for practical advice: it’s this. Be polite. Document everything. Keep a log. Follow...
11 months ago
Why is Jepsen Written in Clojure?
People keep asking why Jepsen is written in Clojure, so I figure it’s worth having a referencable answer. I’ve programmed in something like twenty languages. Why choose a Weird Lisp? Jepsen is built for testing concurrent systems–mostly databases. Because it tests concurrent systems, the language itself needs good support for concurrency. Clojure’s immutable, persistent data structures make it easier to write correct concurrent programs, and the language and runtime have excellent concurrency support: real threads, promises, futures, atoms, locks, queues,...
about 1 year ago
Finding Domains That Send Unactionable Reports in Mastodon
One of the things we struggle with on woof.group is un-actionable reports. For various reasons, most of the reports we handle are for posts that are either appropriately content-warned or don’t require a content warning under our content policy–things like faces, butts, and shirtlessness. We can choose to ignore reports from a domain, but we’d rather not do that: it means we might miss out on important reports that require moderator action. We can also talk to remote instance administrators...
over 1 year ago
10⁹ Operations: Large Histories with Jepsen
Jepsen is a library for writing tests of concurrent systems: everything from single-node data structures to distributed databases and queues. A key part of this process is recording a history of operations performed during the test. Jepsen checkers analyze a history to find consistency anomalies and to compute performance metrics. Traditionally Jepsen has stored the history in a Clojure vector (an immutable in-memory data structure like an array), and serialized it to disk at the end of the test. This...
over 1 year ago
Fast Multi-Accumulator Reducers
Again with the reductions! I keep writing code which reduces over a collection, keeping track of more than one variable. For instance, here’s one way to find the mean of a collection of integers: (defn mean "A reducer to find the mean of a collection. Accumulators are [sum count] pairs." ([] [0 0]) ([[sum count]] (/ sum count)) ([[sum count] x] [(+ sum x) (inc count)])) This mean function is what Clojure calls a reducer, or a reducing function. With...
over 1 year ago
Monkeypox in Ohio
Update 2022-08-12: The Hamilton County Health Department now has a page about monkeypox with symptoms and isolation guidance, as well as options for vaccination, testing, and treatment–look for “complete our monkeypox vaccine registration”. The Cincinnati Health Department is also offering vaccines for high-risk groups. People in Hamilton County without a primary care physician who have symptoms can also call call 513-357-7320 for the Cincinnati city health clinic. If you’re a gregarious gay man like me you’ve probably heard about monkeypox....
over 2 years ago
Loopr: A Loop/Reduction Macro for Clojure
I write a lot of reductions: loops that combine every element from a collection in some way. For example, summing a vector of integers: (reduce (fn [sum x] (+ sum x)) 0 [1 2 3]) ; => 6 If you’re not familiar with Clojure’s reduce, it takes a reducing function f, an initial accumulator init, and a collection xs. It then invokes (f init x0) where x0 is the first element in xs. f returns a new accumulator value acc1,...
over 2 years ago
A History of Leather at Pride: 1965-1995
This history is also available as a PDF or EPUB, which may be more pleasant for reading. You can also download the full BibTeX database for this work. If you have a story you’d like to share, you can email aphyr+leather-history@aphyr.com. The 1979 Gay Freedom Day Committee will apparently take the advice of its March Subcommittee and not attempt to bar persons who appear in chains, leather and other bondage symbolism in the eighth annual parade on June 24. Several...
over 3 years ago
Site Redesign
Hey y’all! It’s been, gosh, what, ten years? I finally finished a total site redesign: all-new backend, HTML, CSS, modern image formats, etc. It’s finally readable on mobile now! There’s a lot of accumulated cruft in the database and filesystem–aphyr.com is old enough that it still has redirects for CGI scripts written circa 2005. While I’ve tried as hard as I can to preserve compatibility, older posts may not look great, or there might be subtle formatting/text-processing issues. If you...
almost 4 years ago
Maintenance Downtime
Hey y’all. Doing some long-overdue upgrades on aphyr.com; service will be up and down for a few hours; emails might bounce, etc. as I get things sorted. Update: All finished, thanks for bearing with me!
almost 4 years ago
Unifying the Technical Interview
Previously: Rewriting the Technical Interview. Aisha’s hands rattle you. They float gently in front of her shoulders, wrists cocked back. One sways cheerfully as she banters with the hiring manager—her lacquered nails a cyan mosaic over ochre palms. They flit, then hover momentarily as the two women arrange lunch. When the door closes, Aisha slaps her fingertips eagerly on the pine-veneer tabletop. Where have you seen them before? But she is giggling and glad to finally meet you, and her...
about 4 years ago
Rewriting the Technical Interview
Previously: Typing the Technical Interview. Update, November 2023: here are the full term rewrite and language macros which formed the seed of this story. These files include OO notation as well as the basic Algol syntax shown here. There is also a sketch of an object-oriented language with classes and inheritance, implemented as a Clojure macro. I do not remember writing it. It looks terrifying. Frigitt, vi danser For et øyeblikk, vi leker Vi tusen små bladskiper Gleder oss, på...
over 4 years ago
Clojure from the ground up: polymorphism
Previously: Debugging. In this chapter, we’ll discuss some of Clojure’s mechanisms for polymorphism: writing programs that do different things depending on what kind of inputs they receive. We’ll show ways to write open functions, which can be extended to new conditions later on, without changing their original definitions. Along the way, we’ll investigate Clojure’s type system in more detail–discussing interfaces, protocols, how to construct our own datatypes, and the relationships between types which let us write flexible programs. Thus far,...
over 4 years ago
A Satisfactory Way of Building
Update 2022-03-31: Owen Jacobson has written a lovely companion to this piece which covers new dynamics in update 5. With apologies, as usual, to Christopher Alexander. Satisfactory is a first-person factory construction game. COVID-19 has given me license to spend FAR too much time playing it, and I’d like to share a few thoughts that I hope might prove useful, or at least interesting. This is a pattern language: a grammar which generates buildings. Each of the patterns identifies forces...
over 4 years ago
Stay Home
Stay home. I’ve been talking to folks 1:1 about this, but from a scroll through the feed today, I don’t think the general community has caught on. COVID-19 is not fucking around. If we don’t contain or dramatically slow it, we are going to run out of health care workers, hospital beds, and equipment. People are going to die for want of care. This is not a problem of the distant future: recent modeling suggests that without a significant reduction...
almost 5 years ago
Needlepoint
Inspired by Peter Watts’ The Freeze-Frame Revolution and The Island. Each birth is violent in the same way. I erupt into the void, my mirrored surface riotous with gamma radiation, parafluid sheeting from my forced extremities, ripped away by gravitational shear beyond all comprehension. Terrible heat, terrible light: the exotic metals of my placenta flash-vaporize, ionize, and crackle around me, an expanding plasma aglow with the fire of the aperture’s parturition. Spacetime snaps flat, rebounds. The brilliance fades. Lightning heralds...
almost 6 years ago