Yes, that’s right. Everything except for Javascript’s usual dynamically checked types are erased.

This analysis looks like a useful public service! Thank you, considerate netizen!

I’ve already conceded on point 6 that types are not technically functions, and that I’m making an analogy. I think analogies are in the territory of opinions.

If you really want to argue technical correctness on point 5 then let me try to illustrate more clearly what a type parameter list is. First I’ll cite some sources to clarify terminology.

From the Wikipedia article on Generic programming (emphasis mine):

Generic programming is a style of computer programming in which algorithms are written in terms of data types to-be-specified-later that are then instantiated when needed for specific types provided as parameters.

That sentence cites the book “Programming Languages: An Active Learning Approach” by Kent D. Lee, which uses both the terms “type parameter” and “type argument”.

The Typescript Handbook page on Generics uses the terms “type parameter” and “type argument” many times. Here are some excerpts:

The type of generic functions is just like those of non-generic functions, with the type parameters listed first

Generic classes have a generic type parameter list in angle brackets

(I know we’ve been talking about functions, not classes. But both have type parameter lists, and it’s the same concept in both cases, so I think this line is relevant.)

When we use GenericIdentityFn, we now will also need to specify the corresponding type argument

I think we can clearly establish this terminology as it relates to one of the examples from my article:

function useState<S>(initialState: S): [S, (value: S) => void] { /* ... */ }
//               ╰┬╯
//       This is called a "type parameter"


//       This is called a "type argument"
//       ╭────────┴──────╮
useState<"open" | "closed">("open")

And you can see here how type arguments bind to type parameters in a way that is directly analogous to value arguments binding to value parameters:

function useState<S>(initialState: S): [S, (value: S) => void] { /* ... */ }
//               ╰┬╯ ╰────────┬─╯
//                │           └────────────────────────┐
//                └───────────────────────┐            │
//                               ─────────┴────        │
//        type argument binds to type parameter        │
//        ────────┬────                                │
//                │                             ───────┴───────
//                │     value argument binds to value parameter
//                │     ──────┬───────
//       ╭────────┴──────╮  ╭─┴──╮
useState<"open" | "closed">("open")

Your counterargument that “Generic functions can have the type specified” is just a different way of saying that a type argument binds to a type parameter.

Just in case the issue is with the use of the word “list”, a generic function can have multiple type parameters. Thus, a list. Here is another example from my article that demonstrates a list of type parameters:

//                  Two type parameters make a list
//                   ╭────────────┴─────────────╮           
function getOrDefault<Obj, Key extends keyof Obj>(
  obj: Obj,
  key: Key,
  def: NonNullable<Obj[Key]>
): NonNullable<Obj[Key]> {
  const value = obj[key]
  return value != null ? value : def
}

Note that getOrDefault has a type parameter list, and also has a value parameter list (or simply “paremeter list” if you prefer). Therefore it has two parameter lists.

Is the problem that when I use the words “parameter list”, to you that means specifically what I’ve been calling value parameters? And that’s not the same thing as type parameters? I think I’ve been very clear that I’m talking about two lists with different kinds of parameters. If that’s the issue then please make some allowance for the way I’m using terminology, and for the context in which I’m using it.

Maybe the issue is that functions can be called with only value arguments? Or that non-generic functions don’t have a type parameter list? I think I addressed this in my article. Type arguments are implicit, so they can be omitted from call sites. But the type parameter list exists in the generic function definition either way. A non-generic function doesn’t have a type parameter list - but I think an equally valid interpretation is that it has an empty type parameter list, which is expressed in the language by omitting the angle brackets.

Anyway, there’s no way you can say it isn’t true that some functions have two parameter lists when type parameter lists are a thing, and value parameter lists are a thing, and generic functions have both.

You can say that I’m overgeneralizing by saying that all functions have two parameter lists when actually only generic functions have two parameter lists. But I think you’d have to be pretty pedantic to say that makes my point wrong. I think it would be glossing over a nuance. If this is the point you disagree on then let me know.

Or you can say, as I do, that all functions do have two parameter lists, but for non-generic functions the type parameter list is empty, so we don’t write it. That’s my interpretation - or in other words, my opinion, which is not a matter of fact.

This is kinda how I react when I see people praising Golang. I do understand the feeling of being triggered by a language you find frustrating!

As the author of the referenced post, I think Typescript serves a different purpose from Purescript. I disagree that type checking isn’t valid if it’s not incorporated in a compilation process. If there is a mechanism for demonstrating that types accurately describe runtime behavior, that’s type checking. But I do agree that Purescript and Haskell are closer to correct, and are more robust. So if you’re leaning on type checking for correctness, you’re going to fall over less often with those languages. But not never! I’ve tinkered with Purescript a little, and I’ve worked with Haskell extensively, so I am acquainted with the differences.

I actually used to work with Phil Freeman; but I never got around to talking to him about Purescript. What an opportunity I missed!

atrocious code block font

That’s author’s perogative I’m afraid. But if you have more specific feedback I’ll listen. For example, I’m thinking maybe you object to the handwritten italic font? I like to use that italic for keywords, because I recognize those by shape instead of by reading anyway. I think the use of italic helps me to skim over the keywords, and focuses my eyes on the non-keyword words that I need to pay more attention to. But then there’s always the question of where to draw the line. Like, should built-in types like number and string be italicized?

some of non-code annotations are misaligned (on phone) e. g. nullable string

Thanks for pointing this out! It turns out my monospace font doesn’t have glyphs for box drawing characters, and different web browsers were using different fallback fonts with very different glyph sizes. I configured another font for box drawing, and made sure that it uses glyphs with the same size as the other monospace glyphs. (No, I’m still not going to change the font. It’s my favorite, even if it makes me work a little harder.)

5 is about Generics with emphasis on React. functions don’t “take two parameter lists”. Generic functions can have the type specified.

Yes, functions do take two parameter lists! There is a type parameter list, and a value parameter list, clear as day! The type parameter list is how you specify the type. Just like the value parameter list is how you specify the arguments.

That section is intended to help readers to understand generics by explaining it in a way that they probably haven’t seen before. I wanted to relate the unfamiliar concept to a familiar one.

6 is wrong. types cannot “be functions”. You can do some type algebra on types.

Again, I disagree; and I provided multiple examples. I know that generic types are technically not functions. But I think they sort of do the same thing, which is to transform inputs into some output. In most languages in generics it’s not especially helpful to think this way. But in Typescript there is a lot of sophisticated stuff you can do with “utility” types, and I think it’s helpful to think of those as functions, but at the type level. Once again, this is about relating an unfamiliar concept to a familiar one.

But I did add a note to make it extra clear that types are technically not functions, even if they function like functions.

There are programs in some places for rebates for e-bikes. For example my electricity provider does that. Maybe check if there’s something where you live?

It’s intended to acquaint one with the language, and there is a lot do that. I don’t know what is the right way to write this kind of stuff; but my thinking was if I were learning I’d rather start with this kind of piece before getting into a book.

But for the front, there’s nothing which appears to sink energy, apart from what appears to be a conventional disc brake.

Maybe it’s like an electric car, which uses a combination of regen, and disc brakes. Depending on the car I think letting off the accelerator (in one-pedal mode) engages regen, while the brake pedal uses the disc brakes, and does not capture energy. Or in some cars the brake pedal uses regen braking for a portion of its travel, and disc braking if you press harder.

Maybe this bike uses regen when you stop pedaling, and has regular disc brake levers for faster stopping? Or maybe regen back-pedaling?

This reminds me of another e-bike made by a car company, the Ford Bronco (youtube link). But that one is an entirely different idea - it’s an expensive and not very practical mountain bike.

This Rivian one makes me wonder where muscle power from pedaling goes? Is it wasted? Is it all captured as regen? To me biking is a lot about efficient travel, and electric range is important. On a typical e-bike muscle power translates into forward thrust with efficiency somewhere over 95% (based on my vague understanding of bike efficiency). Using pedaling to generate electricity to run a motor will drop that efficiency to something like 30%, I think? That’s a number I heard somewhere for regen brake efficiency on cars. And even on a motorized bike muscle power is significant. My 500 W bike advertises motor output “up to four times the power of a human cyclist”. That implies that muscle input is over 20% of the total power most of the time, even on a high motor setting.

I guess I’m not the target for this bike. It’s probably aimed at people who want to go very fast with no effort. Maybe I should look at it as more of a foot-operated throttle than pedals.

I’m sorry to hear that! I imagine the stiff upper lip tires after a while

I use sops for NixOS, but those secrets aren’t accessed in CI. For actual CI I’ve used a combination of 2-4 above.

There are a few options:

1. Sops-nix or Agenix store secrets encrypted in the repo. Each local machine needs to be set up with a PGP or an SSH key to decrypt and encrypt as necessary. This is what I do with my NixOS configuration.

2. Manage secrets externally to repo code. I like to use direnv; sometimes I configure the checked-in .envrc file to source another file with secrets, that is not checked in.

3. Don’t use secrets locally. If secrets are things like deploy keys, and I want all deploys going through CI, then I don’t want secrets configured locally. Instead running a deploy script locally should be a dry run, which doesn’t need secrets.

4. Generate secrets at runtime. This is for cases where the project runs a cluster of services which need to authenticate with each other. For tests with locally running test services, authentication is confined to this isolated system. So secrets can be generated at test time, and written to env or config files that are not checked in.

Well, I’m in that Nix shop category. For example, I run tests for my OSS project using lots of Python versions. There’s no need to use a Github Actions matrix for that - Nix does it more efficiently. Doesn’t even require containers or VMs. And the whole setup runs exactly the same locally, on Github Actions, or on Garnix. (But Garnix has better Nix caching than other CI runners, so that’s what I use.)

Pidzoom looks very nice! I might give it a try!

Oh, good tip!

Sure, it sounds like you know more than me. So you get the benefit of a collector that isn’t blocked by your body, but you don’t need to turn your head to see the image?

It sounds sort of like the idea is approaching rear radar, but without any batteries

Oh, that sounds handy!

Thanks! It’s an Orbea Diem 30 - the one with a chain instead of a belt. It’s a Class 1 version. I saw it, and was seduced by the shiny. Plus it was on sale.

Yep, I should do this

But it’s not entirely about protecting the bike. When it rolls it can knock into the back of the seat in front of it, and generally make passengers anxious

How is that? Do you mean that week 1 can occur twice? Or is there another issue?

IIUC you can have days at the start and the end of the year that are all in week 1, and those are two different weeks. But one of those would be, let’s say, week 1 year 2025, and the other would be week 1 year 2026. According to the blog post if you have a week 1 at the end of a year the ISO year number for that week is the next year.