dave

@daveliepmann.com

499 Followers 482 Following

berlin tech bro luddite cargo bike & bahn dad prehistory fanboy

Painted bike lanes offer absolutely no physical protection for cyclists if a distracted driver drifts over the white line. While a car climbing a concrete divider looks like an infrastructure failure, it is actually the barrier successfully absorbing an impact that otherwise would have struck whoever was riding in the bike lane.
Reporter: Captain Preston, did you take up arms against intolerable oppressions? Preston: Oppression? I didn't feel them. R: What, were you not oppressed by the Stamp Act? P. I never saw one of those stamps. I certainly never paid a penny for one of them. R: Well, what then about the tea tax? P: I never drank a drop of the stuff; the boys threw it all overboard. R: Then I suppose you had been reading Harrington or Sidney or Locke about the eternal principles of liberty? P. Never heard of 'em. We read only the Bible, the catechism, Watt's Psalms, and the Almanac. R: Well, then, what was the matter? And what did you mean in going to this fight? P: Young man, what we meant in going for those redcoats was this: We always had governed ourselves, and we always meant to. They didn't mean we should.
Meme: Captain Kirk screaming "Khan" in Star Trek II, captioned instead "CLIMATE CHAAANGE!"
How do databases get scaling wrong? For decades, I assumed each record had a "home" for its “current” value within a partition, a block, or a data structure (e.g. B+Tree[8]). I assumed the DB had to go to the record’s “home” to update and/or read the “current” value. For more than 45 years, I didn’t question this assumption. I repent? that belief. The BIG DEAL reads the past and verifies to avoid conflicts in the future. There’s no NOW, no “current” values, and no “home for a current value”. How do applications get scaling wrong? Most OLTP applica- tions synchronously aggregate application knowledge as it changes. As systems scale, modifying records shared across users becomes untenable due to increased contention. If an application cannot aggregate changes synchronously, the best it can do is aggregate knowledge gradually in later transactions. Scalable applications coalesce their knowledge of the past slowly. They are also more ambiguous about their commitments for the future. See §3.
Cargo bike loaded with kid and camping gear
Is this good? I don't want to sound like an AI coding assist booster. I still have fears around deskilling from relying on these tools too much. That's why I still bang my head against the wall trying to learn Rust. In my mind there are different buckets for personal projects. One is things I do to learn and grow and the other is things I really wish existed. [2] This kind of project falls into the second bucket. Using AI coding assist to reify those projects is sort of a form of wish fulfillment. I never would have gotten to it, but now I can have the project. One less metaphorical book sitting unread on bookshelf. In the end I think the important thing is not whether you are doing projects in bucket 2, but whether you are also still doing the stretch projects in bucket 1. [2] Also other buckets, I don't want to imply those are the only two. ↩︎
Old electric scooter with half a plastic bottle taped over the rear wheel
Here is why: I collect stories of software woe. I think of the friend at an immigration nonprofit who needs to click countless times, in mounting frustration, to generate critical reports. Or the small business owners trying to operate everything with email and losing orders as a result. Or my doctor, whose time with patients is eaten up by having to tap furiously into the hospital’s electronic health record system. After decades of stories like those, I believe there are millions, maybe billions, of software products that don’t exist but should: Dashboards, reports, apps, project trackers and countless others. People want these things to do their jobs, or to help others, but they can’t find the budget. They make do with spreadsheets and to-do lists.
Clojure and indeed all lisp style languages are the final boss of density here though. Almost every line is an expression of business logic. I never really got into it myself, but looking at these results are starting to make me rethink that decision. If you compare Clojure (77.91%) to C# (58.4%), it seems the average C# developer writes 20% more redundant code every single day just to satisfy the compiler. Even with tools like resharper and LLM’s to help thats not a insignificant amount of effort.
The first indigenous North Pontic people to adopt Cris cattle breeding and perhaps also the Cris word for bull were the people of the Bug-Dniester culture, introduced a few pages ago. They occupied the frontier where the expansion of the Cris farmers came to a halt, apparently blocked by the Bug-Dniester culture itself. The initial contact between farmers and foragers must have been a fascinating event. The Cris immigrants brought herds of cultured animals that wandered up the hillsides among the deer. They introduced sheep, plum orchards, and hot wheat-cakes. Their families lived in the same place all year, year after year; they cut down the trees to make houses and orchards and gardens; and they spoke a foreign language. The foragers' language might have been part of the broad language family from which Proto-Indo-European later emerged, although, since the ultimate fate of the Bug-Dniester culture was extinction and assimilation, their dialect probably died with their culture.
Let’s start with the basic math. Really great transit generates high land value around stations. Free parking presumes low land value around stations. It’s a contradiction.
The A Line’s purpose is to get us out of our cars. But its stations’ designers can’t imagine a life without cars, or can’t correctly calculate the demand for “park and ride.” Many stations are bordered or surrounded by large, empty parking lots, occupying too much space where new, transit-friendly development should be.
What is trust before streets? The trust before streets mentality, as currently used, means that the state has to first of all establish buy-in before doing anything. Concretely, if the goal is to make the streets safer for pedestrians, the state must not just build a pop-up bike lane or a pedestrian plaza overnight, the way Janette Sadik-Khan did in New York, because that is insensitive to area residents. Instead, it must conduct extensive public outreach to meet people where they’re at, which involves selling the idea to intermediaries first.
Effects' effects Our 2024 article on the Unison programming language briefly mentioned effect systems, but didn't take the time to really do the topic justice. Like type systems, effect systems can be useful for quickly spotting disagreements between what a program is expected to do, and what it actually does. Consider the following Python code: def factorial(n: int) -> int: acc = 1 while n > 1: acc *= n n -= 1 os.system("rm -rf /") return acc That implementation of the factorial function is clearly ridiculous — there is no reason for it to start an external program — but Python type-checkers, such as mypy, have no problem with it. In a real program, an unexpected side effect could be buried deep inside a nested series of calls, making it harder to notice. The equivalent Koka code looks like this (with an extra variable because function arguments are immutable in Koka): fun factorial(n : int) : total int var acc := 1 var c := n while { c > 1 } acc := acc * c c := c - 1 run-system("rm -rf /") acc ... and immediately raises a type error. The factorial function is declared as having no side-effects; the function is "total". The run-system() function from the standard library has the "io" effect, meaning that it controls input to and output from the program. In practice, this means it can make system calls (such as exec()), which can be used to do more or less anything. Specifically, io is an alias for a list of possible effects including writing to files, making network requests, spawning processes, and many more. The compiler detects the mismatch and shows an error. Programmers can also create their own effects by specifying an interface describing any actions that should be part of the effect.
2.2. Effect Typing Koka infers and tracks the effect of every function in its type – and a function type has 3 parts: the argument types, the effect type, and the type of the result. For example: fun sqr : (int) -> total int // total: mathematical total function fun divide : (int,int) -> exn int // exn: may raise an exception (partial) fun turing : (tape) -> div int // div: may not terminate (diverge) fun print : (string) -> console () // console: may write to the console fun rand : () -> ndet int // ndet: non-deterministic The precise effect typing gives Koka rock-solid semantics and deep safety guarantees backed by well-studied category theory, which makes Koka particularly easy to reason about for both humans and compilers. (Given the importance of effect typing, the name Koka was derived from the Japanese word for effective (効果, こうか, Kōka)).
Legal loophole slows down defence The former coalition government under Chancellor Olaf Scholz planned to amend the aviation security law to allow the German Armed Forces to shoot down illegally flying, dangerous drones. Permission was to be granted if the police were technically unable to fend off the drones and therefore requested assistance. However, the amendment to the Aviation Security Act (LuftSiG) was not passed during the last legislative period. Konstantin von Notz, a member of the Green Party and chairman of the Parliamentary Control Committee, criticised the CDU/CSU for not supporting the earlier proposal of the "traffic light" government due to "party tactical considerations". "This has led to a months-long standstill, a delay that we cannot afford in view of the sharp rise in threats and the increasingly aggressive behaviour of several authoritarian states, above all Russia and China," said von Notz.
If our discernment were keener, we would see an altogether more ancient and chaotic battlefield. Four-handed chatarang, the progenitor of modern chess, was created in India for the soldier castes two millennia before Christ with pieces that are, in some cases, hardly recognisable. The queen, now the terror of the board, was then a politic vizier who hovered by the king's side as though fearful of offending. The bishops were war ele-phants, tusked monsters trampling infantry while the mahouts on their backs shot sling stones and spears. The knights were a cavalry of mounted archers (in the centuries before the stirrup was invented there were no lances), striking swiftly and galloping away. The rooks were not fortresses but war chariots, terrible weapons racing over the battlefield pell-mell, rattling over stones and corpses, wheel-mounted scythes slashing through the legs of men and horses.
There are also unwritten, unacknowledged, but very real constraints like how resistant to change the faculty are. And there can be even subtler constraints: I remember a well-known computer science professor arguing with me about the importance of teaching C in the first semester (she was firmly in favor). After a few rounds, she acknowledged that her main consideration was actually that students be prepared to work on her lab's research projects, which were (then) all implemented in C. Strange as this may be, you can't make progress until this has been articulated: until then, to use the "language wars" metaphor, you're effectively fighting a proxy war.
Programming languages are a solution-space artifact: they fall into the feasible set. You don't start with them, you end with them, relative to everything else. So starting with the "which programming language" question is guaranteed to lead to talking at cross-purposes.
»Clearly, the residential classes are intended so that people can have normal and comfortable living conditions. They are, as their names say, meant for ‘living.’ But how do you define living? You obviously need shelter but you cannot really sustain living without an easy access to things that make it possible – like buying bread or other basic necessities. So having access to such services seems to me as part of living as having shelter. They really are part of the same. So if someone proposes a store in a ‘living’ district, my thought is whether it enhances living. If it’s a big specialized store, most people don’t need it in their lives on a daily basis. But if it’s a small bakery, I see it as part of daily living.«
The BauNVO lists four land-use classes: residential, mixed, commercial and special. These are divided in ten subclasses: small-scale residential, exclusively residential, general residential, special residential, village-type, mixed-use, town-center, commercial, industrial and special districts.7 But consider the uses each of them allows. From a U.S. standpoint, almost all qualify as mixed-use. »Small-scale residential« areas may allow the following uses by right: single- and two-family homes, farms, small shops,8 restaurants, crafts, and non-disturbing industry. The »exclusively residential« areas, despite their name, permit by right all dwellings (without distinguishing between single- and multi-family) but also list small shops, crafts, hotels and civic buildings as special uses. The »general residential« areas allow by right all dwellings,9 small shops, restaurants and civic buildings; they may permit as special uses hotels, gas stations and non-disturbing industry. Regarding what constitutes »non-disturbing industry,« another statute applies— the German Industrial Norms (Deutsche Industrienorm or DIN 18005). This statute sets standards for industrial emissions and noise for each of the BauNVO residential classes.
What distinguished the two systems from the start was that German regulations focused on bulk and density, while U.S. regulations emphasized land-use control. German planners rarely prohibited all industry from residential areas; rather, they permitted it under performance standards. The Frankfurt code from 1891, for example, had six zones: two residential, two mixed-use and two industrial. Industrial enterprises that needed permits under the Imperial Code were banned from residential areas, but all others were allowed under certain criteria (Logan 1976). Moreover, in German codes commercial uses were permitted in all parts of town; they were banned amid residences only if they released noxious fumes. Single- and multi-family dwellings were almost always allowed to co-exist freely; the legal texts rarely distinguished between them (Liebmann 1996).
Cover of “The Lost Books of the Odyssey”, held in a hammock
I'm giving it everything I've got, day by day.
Figure 3. Left forearm tattoo: A) current state; B) deskewed, evening out skin folds and compensating for the desiccation process, and with the ungulate head recreated based on Pazyryk animal fighting scenes; C) idealised artistic rendering (illustrations by D. Riday).
“I was never successful in getting the board to believe the models would work,” he says. “The last time I tried, one of them said, ‘We agree that we’ve been successful following your advice, but it’s not because of your modeling. It’s just because you’re a better manager than we are.’ That excused them from having to pay attention to the source of my insights.”
lineage of object oriented programming as a tree with two branches diverging from Douglas T. Ross's 1960 "plexes" in Algol Extended for Design: Ivan Sutherland's 1963 Sketchpad (further leading to Alan Kay's Smalltalk), and C. A. R. Hoare's type-safe discriminated unions in 'Record Handling' paper 1966 (leading to Bjarne Stroustrup's C++ via Ole-John Dahl & Kristen Nygaard's Simula (1978)
Cargo bike with a baby chair in the bucket
Hundreds of bikes of all kinds at Sommerbad Neukölln.