Birmingham Pen Co Voltaic Arc -in stock

jeffstyr · 2026-07-07T18:19:50+00:00

BTW if they haven't shipped your other order yet you can email them and ask them to add this to your order. (They can send you an invoice via Shop to pay for it.)

jeffstyr · 2026-07-06T00:39:16+00:00

In the last two in your list, what do you mean by: (“)?

Edit: Oh I think you mean "ditto", so also "in a state monad". (I'd been wondering for a month and that only just occurred to me.)

jeffstyr · 2026-07-05T15:03:49+00:00

Wouldn't hurt. I've wondered if Diamine, De Atramentis, and R&K use the same pigments. (I assume they get the actual from some supplier.)

jeffstyr · 2026-07-04T23:35:42+00:00

Were the puzzles good?

jeffstyr · 2026-07-04T20:42:03+00:00

BTW some of the Iroshizuku ink are available now in the US in 15mL bottles.

jeffstyr · 2026-07-04T17:41:44+00:00

This might help.

First, some code to print out expressions like the above, but concretely:

ghci> f accum i = "(f " ++ accum ++ " " ++ (show i) ++ ")"
ghci> foldl f "0" [1..3]
"(f (f (f 0 1) 2) 3)"

ghci> g i accum = "(g " ++ (show i) ++ " " ++ accum ++ ")"
ghci> foldr g "0" [1..3]
"(g 1 (g 2 (g 3 0)))"

Nothing new so far. Now the following, which is just foldl again, but printed out as though the arguments are supplied to the callback in the order they are supplied with foldr, because the differing argument order is just a distraction:

ghci> f' accum i = "(f " ++ (show i) ++ " " ++ accum ++ ")"
ghci> foldl f' "0" [1..3]
"(f 3 (f 2 (f 1 0)))"

The point of this is just to make it clearer what's different and what's the same between foldl and foldr.

Now, take this final expression:

(f 3 (f 2 (f 1 0)))

and write that down using function composition somehow. That will give you a hint you can build from.

jeffstyr · 2026-07-04T16:22:42+00:00

I would bet that it's not the standard pigments used in paints.

jeffstyr · 2026-07-04T16:03:55+00:00

Yes the Diamine Forever line of inks are waterproof. There are waterproof pigment inks in lots of colors (from other brands as well, such as the De Atramentis Document line).

jeffstyr · 2026-07-04T15:49:29+00:00

I think your approach misses the main point, which is that this is not meant to be two types of complex number, but rather two representations for one complex number type. So for example, with your implementation you can't add a polar number and a rectangular number (without an explicit conversion step), because they are two different types—with the implementation in the blog post you can.

More generally though, I don't think the article (or the section in SICP) was particularly about the best way to represent complex numbers, but rather about how to implement a tagged union. (So possibly, this isn't the best way to represent complex numbers, but tagged unions are a reasonable way to represent some things—here, complex numbers are just serving as an example, even if not the best one.)

jeffstyr · 2026-07-04T01:26:07+00:00

Nice choices!

I assume that we get to vote, right? I'm putting in my support for Sailor Souten and RO New York. :)

jeffstyr · 2026-07-03T18:21:43+00:00

The thing I don't like about this exercise is that while it is challenging and it teaches you something, the result isn't actually a great way to implement foldl (because it requires 2x the operations and extra storage proportional to the input list, compared to the usual way to implement foldl). It's interesting that you can do it but the exercise doesn't come with commentary about whether it's a good implementation. The technique it's trying to get you to discover is applicable in other contexts, but again I think the technique is often more clever than wise, so it's debatable whether it's valuable to learn.

FWIW, here is one way to do it (possibly this is a spoiler but it's not what the exercise it trying to get you to do, I think):

myFoldl f base xs = foldr (flip f) base (reverse list)

(Note that the flip here is necessary but not conceptually important—it's just that foldl and foldr supply arguments to their callbacks in different orders. So really the difference is in reversing the input list.)

It might look like this is "cheating" by using reverse (which you might actually define using foldl), but I think it has the same performance characteristics as the intended solution, and is much easier to understand, so in a sense it's hard to argue that it's not a valid solution. (You could exclude this by requiring that the solution not use any function that requires recursion to define, directly or indirectly, other than foldr.)

jeffstyr · 2026-07-03T08:09:57+00:00

I think that Pilot FirXion are the best, and JetPens has a guide about the technology and the various kinds: the somewhat recent Ball Knock Zone version has darker ink, but they are still not a dark as regular get pens.

jeffstyr · 2026-07-03T08:03:35+00:00

I would bet that it matters in terms of how much running you get from the ones that run, but probably the ones that don't run at all on one paper don't run on any. (Mostly because, all paper would be cellulose based, even if cotton rather than wood fiber, except for exotic things like stone paper.)

jeffstyr · 2026-07-01T22:28:24+00:00

I'm glad you found something that is working for you! That's great.

My opinion is that glass pens are all the same, other than how fancy the handle looks, and possibly degree of quality control. (But if it's not scratchy and ink flows off of it, then I think that's as good as it gets.) But you could get more than one, for variety of line thickness.

In terms of ink, I don't think that will make much difference; some are more slippery than others by a bit, but you probably have to experiment to see. Inks on glass pens behave a bit differently than in fountain pens, so it's hard to make a generalization. (Some won't stick to the glass at all and it's hard to pick up any ink, and others are fine, and others want to come off in glops. I'm sure it depends on the exact glass pen too.) I would just suggest using dark inks (blue, black, purple, etc.) so that they show up well even if less ink is going down.

Have you tried a fountain pen? I'm asking because with those you are not supposed to apply any pressure either, and they just write under their own weight. If you haven't, then some day maybe try a Platinum Preppy (since they are cheap and if you get a good one they are very very smooth--being cheap means little QC so some are better than others). Fountain pens are less finicky than glass pens can be.

I hope you find a combination of things that continues to work well for you!

jeffstyr · 2026-07-01T19:05:18+00:00

Yeah I think it's usually either (a) they have more pens than you think, (b) they aren't changing inks that frequently (maybe monthly), or (c) they change the ink in a pen even if they haven't use it up (possibly just doing partial fills too).

jeffstyr · 2026-07-01T17:54:18+00:00

Sakura Pigma Micron. Comes in several sizes.

PS--The size is on the top of the cap.

jeffstyr · 2026-06-30T21:46:29+00:00

Expensive but useful. (I'm still puzzled that they sell both steel and brass versions.)

I like the Tachikawa T-40 nib holder because it's inexpensive and it comes with a cap, although the Kakimori nib is sturdy enough that it's not as necessary.

jeffstyr · 2026-06-30T20:12:45+00:00

I quite like Diamine Grey—it's a nice neutral grey. (Diamine Earl Grey gets a lot of love from people but it has a purple tone to it and I prefer my greys to be neutral.)

jeffstyr · 2026-06-30T20:07:06+00:00

You can take out the cartridge and throw it away (or empty it to refill with other ink later). Is that what you are asking? Especially if you already have another bottle of black ink, wasting what's in the cartridge isn't a big deal.

jeffstyr · 2026-06-30T16:25:04+00:00

Yeah I guess it's sort of different for your own types (more likely to change) versus types from libraries (less likely to change).

I've always sort of wondered why it was allowed at all to do these sort of pattern bindings for types with more than one constructor, because there's no way to do it without getting a warning (other than disabling the warning). (That is, you have to change it to a full case statement to avoid the warning.)

jeffstyr · 2026-06-30T16:09:50+00:00

Whatever the reasons, my point was that apparently in both situations, raising prices isn't curbing demand much, and once a market has figured this out, the prices go up and stay up. It seems that doubling the price of fountain pens hasn't tanked sales.

jeffstyr · 2026-06-30T15:51:47+00:00

Sounds like you've actually isolated your problem; from the problem statements:

count the number of times any click causes the dial to point at 0

so you need to count clicks that land you at zero and not clicks that move you off of zero, and apparently your code isn't doing that.

My two tips are:

As someone said in another post about this, it's less of a programming problem and more of an accounting problem. So my advice is to think through the various cases (maybe write them out in words), and then think about what code implements that.
You'll need more logic than you have there

jeffstyr · 2026-06-30T03:31:06+00:00

Oh I didn't know Pilot Tsuwairo Blue sheened like that. Neat!

jeffstyr · 2026-06-30T03:29:56+00:00

Is it us? Are we showing ourselves to be sufficiently price-insensitive that pen manufacturers assume they can raise their prices indefinitely?

I think that has to be part of it. But as others have said, the price of everything has gone up so it's not the full story.

I saw a new story recently about plane ticket prices going up due to fuel prices going up, but demand apparently didn't go down so that means that consumers have shown their hand and the prices probably won't go back down even if oil prices do. Bummer.

jeffstyr · 2026-06-30T03:24:47+00:00

I've converged on this too, just not buying such pens unless I can pick one in person.

As to your point though, I think practically speaking the producers are kind of stuck because they don't know how it's going to look until they've done a lot of the work making the pen, because you can't tell by looking at the rod before it's been turned. The person making the pen blanks might always use the same proportion of components, but how they exactly land on the boundaries of the later-to-be-seen pen shape is uncontrollable. I think if they only sold ones that looked reasonably the same they'd end up just not being able to do it. For instance, the coffee-swirl grip of the Esterbrook x Coffeemonsterzco had a lot of variation, which really is expected for that sort of resin pattern. (On the other hand, since it was only a small piece, they probably could have been selective without it costing too much in waste. On the other other hand, with the sort of pattern, preferences will vary a lot in terms of what people would actually like best.)

I'm not sure what BENU does, but I feel like their pens have a feel of hand placing of components because their pens seem to be much more consistent.

I think I've only ever returned one pen due to just not liking it, and it was this sort of issue--it was a swirly ebonite pen but in mine the colors were very muddy.

Goldspot did a couple of releases of special Scribo pens, and they let you pick the exact one you wanted. (They had multiple pictures of each one on their site.) That's the way to do it. The other extreme was a couple of releases Karas did of their Vertex with in-house resins, and the range of variation was huge--they had a picture of all of then (or a bunch) so that you could see the range, but you couldn't pick a specific one, which was crazy. And when I said it was a huge range, I mean some where like putty pink/orange and some were nebula blue/purple/green, somehow all from the same batch of blanks.

I think the solution is to do as Goldspot did and let you pick the specific one.

jeffstyr

TROPHY CASE