For everyone who would like to know where Santa gets the presents from: youtube.com/watch?v=eCMjJ1epreQ

@JosephWright what are the reasons to use str_foldcase over str_lowercase?

@Bob Case folding is for programmatic data, and for example converts both internal and final sigmas to the same codepoint - I only included string lowercasing as it's needed for example to auto-generate command names - text is different

@Bob This isn't really a TeX-specific question, I only know that "it has something to do with Unicode and multilingual text"

@user202729 Well sort-of: Unicode wouldn't have a 'programmatic' lowercase function at all, but we needed one for use inside \csname constructs

Hm? What do you mean?

Unicode defines what fold-case means, no? And LaTeX need one for use in what?

@user202729 Case folding is for 'programmatic' application, upper/lowercasing for text - the problem for LaTeX is \csname ...\endcsname is programmatic but case folding isn't right - people want things like \csname \str_uppercase:n {#1} \str_lowercase:n {#2} \endcsname

... by "programmatic" do you mean "expandable"? Of course if you program in LaTeX everything you write is programmatic?

Hm wait

Okay maybe the reason I can't understand is I don't know what case folding is

Let me read up

@user202729 'Programmatic' is nothing to do with LaTeX specifics here: it's about the use case of the text

@user202729 unicode.org/faq/casemap_charprop.html

Okay I think I did understand it correctly, casefold is used for case-insensitive comparison and case mapping (uppercase/lowercase) is used for display to the user

@user202729 Yup

So... what's wrong with my original message?

By the way how much should I try to solve question before posting? If I research too much I end up posting a self-answer somehow ("reasonable amount"?)

@user202729 Only that the Unicode descriptions don't really address the 'construction of programming keywords' situation, so I had to make a judgement

Also – the ✩ functions can all be implemented as ⋆ right? By moving the result around when dump them at the end (was going to write a main question "is there any ✩ functions that cannot be implemented as a ⋆ function?", but a bit too lazy to write a proof of concept \tl_map_function:nN that is ⋆-expandable)

@user202729 With \expanded available, any rEXP function can be fully expanded, so it's not worth the effort

Ah right, \expanded is itself f-expandable, so take it as a curiosity question then

"Without \expanded primitive, is there anything that can be computed with a x-type expandable function but not with a f-type expandable function?"

@user202729 Nothing comes to mind: it's a question of effort but also of performance (making code f-type expandable is quite a bit of work)

@user202729 Bruno's emulation code for \expanded in older engines is of course done using only 'classical' primitives, so it is making stuff e-type expandable

That one doesn't count because it's emulated with unexpandable TeX

Wait

It's a different thing? Okay I guess. (never seen it)

Just make a compiler to compile some readable source code to f-expandable functions, then, less effort

@user202729 No

Yes, I realized what it's about (see later message)

@user202729 Emulating \expanded is doable but it's a lot of effort: it has to be expandable at the end of the process

@JosephWright but it's not the same as \expanded, it just allows e-type. You can't do things like \expanded{\expandafter}\stuff with it.

(nonetheless it's brilliant code)

@Skillmon Well yes, but the discussion here is about expl3 functions

Meanwhile, refactor time ...

@user202729 \keyval_parse:NNn isn't depending on the surrounding context, as it wraps the results of each element in \exp_not:n you have to pay attention on how to use it. When \expanded is available and you use it everything works out how you want, but without using \expanded yourself you can only make it ⋆ by moving stuff after a marker reliably outside of an e or x expansion context, or you'll have to make sure that your follow-up code is also protected in an \exp_not:n and [...]

[...] your marker isn't expandable (so has meaning \relax or is \protected).

@Skillmon It's doable using the stack if you put in enough effort [I do have some experience of this ;)]: A more important question for me is do we go the other way (faster code) when we decide to require \expanded

@JosephWright well, currently \keyval_parse:NNn has two implementations and if \expanded is available the more robust and faster one is chosen.

@JosephWright and yes, it's doable (see my "or you'll have to make sure ...")

@Skillmon I was meaning for things that are currently f-type could be reimplemented to be clearer

@JosephWright aahh, sorry I misunderstood that one :)

"because TeX is a terrible programming language, the maintainer is to do a lot of work now"

Maybe it's easier if backwards compatibility can just be dropped. Implement with directlua

@user202729 you would have to not just backwards compatibility, cross engine compatibility would have to go, we are nor really in a position to drop pdflatex, platex, or even xelatex.

That counts as backwards compatibility too. If you integrate Lua magic expandable commands into pdftex it becomes another engine already

@user202729 integrating lua into all engines isn't really an option (and why would you do that rather than switch to luatex)

I wonder if things here in chat work the same way as with Bloody Mary: say "expandable" three times in a row and a pink rabbit will magically appear

ooh

expandable

expandable

expandable?

ooh

now we wait

I love this chat

dinner

@DavidCarlisle oh no

@PauloCereda it's not pink :-(

@Rmano oh

@Rmano It is red and white. If you watch it from some distance, it will look pink :)

(and if I were @DavidCarlisle I would be able to point out another approach of making the rabbit look pink)

@samcarter oh, right.

@samcarter and the duck

@DavidCarlisle oh no!

What is the english name for the extra white space in a glyph? For example, in the parenthesis that I will paste below, there is some extra white space around the parenthesis that is still inside the box. In Swedish it is "kött", which might be translated into "meat".

@mickep -- This might conceivably be called an "open counter", but that's just a guess.

@barbarabeeton Thanks! (Then I like the swedish term better.)

@mickep ... so these world famous Köttbullar from this furniture store are just balls of extra white space?

@samcarter Oh no. :)

Think of the parenthesis as the bone. Then the space around it is the meat.

@barbarabeeton Looking around, it seems as if the open counter is only the space that is in the "convex hull" of the character (in the case of the parenthesis the area beteween the tips that is also from the exterior of the character. (In the case of an o, the interior of the o is called a lake counter it seems.)

@mickep that's a nice explanation to remember the word :)

@samcarter Oh, glad if it helps :)

@mickep -- I can't find anything more applicable online. I'll ask some typographically educated friends.

@barbarabeeton I'll take some steps (3m) to my book shelf as well. Thanks!

@barbarabeeton It seems to be called side bearing. Found it in Felici's book.

@mickep -- No, side bearing is the "extra" space external to the shape of the glyph, giving the space that keeps the visible shape from bashing into whatever is next to it. Picture a piece of metal type.

@mickep sidebearing, but seems you found it already:-)

@barbarabeeton yes but isn't that what the picture shows, therectangle is wider than the visible )

@barbarabeeton That is what I tried to ask for. Sorry if my description was bad.

@mickep see the marked areas in designwithfontforge.com/en-US/Spacing_Metrics_and_Kerning.html

@DavidCarlisle Thanks! But don't you also like the word "meat" better? In particular when working with dafont.com/duck.font

@mickep why meat?

@DavidCarlisle The character itself is the bone.

@mickep ah. It always helps to know the image behind the word usage:-)

@DavidCarlisle Certainly.

@mickep presumably early Danish typographers were already used to X-ray photography where the bones show up and flesh is space. Obviously far more advanced than the English.

@DavidCarlisle Oh!

We should watch out for @daleif, he is most likely way ahead of us...

@DavidCarlisle on german keyboards you can use \c_blub_basket_clist

@UlrikeFischer it would make @egreg happy