TeX, LaTeX and Friends - 2019-09-25

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Robert Marshall Murphy

1:05 AM

I'm attempted to make a \newcommand with expl3 and I've just about broken my poor brain. I'm not enough of a programmer to mix regular, macro design with this!

2 hours later…

3:32 AM

twitter.com/CodeWisdom/status/1176542079297757184?s=09

3

3:45 AM

@DavidCarlisle Isn't the motto yours? ^^^

@DavidCarlisle They had green ducks as gadgets well before tikzducks package was written

3 hours later…

6:46 AM

@CarLaTeX :-)

@RobertMarshallMurphy in some future world that may be the "regular macro design" and you should be able to do whatever you need without mixing styles but we are not there yet, so for now, it is what it is.

6:59 AM

@DavidCarlisle I don't think that it is fixed, the issue is still open github.com/latex3/latex2e/issues/52.

@UlrikeFischer yes I had a version that had providespackage and typeout working (but other stuff broke:-) we should probably look at that again.

7:30 AM

@JosephWright as far as I can see they compare "start version of tl19" with "start version of tl18". I'm not sure if this is really so useful and needed. But I'm rather surprised that they don't "repair" the microtype problem - it would be easy to add a newer version. Instead they expect their user to add luatexbase.

7:50 AM

@RobertMarshallMurphy Not sure I follow

@UlrikeFischer Well yes, I assume they use a fixed TL version, so likely the DVD ISO one

@UlrikeFischer Might be worth asking them about that: I think they would listen (and I've joined twitter so I can tweet them!)

@JosephWright yes, try. We don't want a new bunch about questions, "why does microtype break", even if we can link to answers and their blog ;-).

@UlrikeFischer In other news, working on the texmf idea for l3build, I'm getting some very odd errors for luaotfload: expect a mail

8:14 AM

@JosephWright ok.

@UlrikeFischer Mail sent to team: some file is being picked up that I'm missing

@UlrikeFischer twitter.com/texdevnet/status/1176772595968020486

1 hour later…

9:22 AM

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4

@DavidCarlisle ^^ I think @CarLaTeX is mean

1 hour later…

10:51 AM

@egreg \expanded FTW ;)

@UlrikeFischer Overleaf have updated their blog post

@JosephWright you are causing havoc in Twitter

@UlrikeFischer texmfdir now working: l3build release sent

@JosephWright 😉

@JosephWright ooh

@egreg Need TL'19 pdfTeX ... on Overleaf ;)

10:57 AM

@JosephWright @DavidCarlisle did you enjoy BJ's speech on the UN?

@PauloCereda Didn't watch that, but have BBC on now

@JosephWright I am watching on YouTube

@JosephWright Parliament, I guess?

@PauloCereda Yes

@JosephWright me too

@JosephWright "There will be no prorogation..." (me: ooh) "... that does not comply..." (me: oh)

@JosephWright can we bring Brian Blessed to the House of Commons?

11:28 AM

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@DavidCarlisle ^^ I think @JosephWright is mean

12:06 PM

@JosephWright I didn't meant that they should mention the problem (and its work-around), but solve it - by updating locally microtype.

12:31 PM

@PauloCereda I wanted to give the correct attribution

@CarLaTeX :)

1:11 PM

@UlrikeFischer I suspect they want a 'known quantity' TeX Live installation: they can say clearly at present exactly which one you get, and they are aiming to roll out TL'19 soon anyway

1 hour later…

2:12 PM

@barbarabeeton which question?

Phelype Oleinik

1

Q: My question is a duplicated of a closed question

I wanted to auto-flag my well-recieved question which is a duplicate of a closed question but unfortunately, the closed question doesn't have an answer to it. How can I deal with this ethical issue?

feature-request duplicates closed-questions

@JosephWright et al. -- Please take a look at this question and the comments that follow: My question is a duplicated of a closed question. There are distinctly problems with the phrasing (and intelligibility) of question titles and of closing reasons. What opinions are there regarding rephrasing titles, or reopening a closed question in order to correct the reason?

2:27 PM

Just had a LaTeX query literal walk into my office :)

@JosephWright ?

@UlrikeFischer One of the students doing more 'physical' chemistry is writing up using LaTeX (on Overleaf), and has a query about my chemstyle package :)

@JosephWright and could you help him or did you sent him to tex.sx? ;-)

@UlrikeFischer Asked for more details :)

@JosephWright "Show the log"?

2:35 PM

@JosephWright "it does not work"

2:50 PM

@JosephWright "Go away, I'm busy" is an acceptable response.

3

@DavidCarlisle I suspect Joseph is too polite to go for that.

@DavidCarlisle ooh

@FaheemMitha to people yes, but students....

@DavidCarlisle orda

@DavidCarlisle He worked it out himself :)

3:06 PM

@PauloCereda spelling

@DavidCarlisle oh

3:26 PM

@DavidCarlisle Students are people too.

@PauloCereda orda?

Are you channelling the Speaker of the House of Commons, perchance?

Just a wild guess.

BTW, I read that the Supreme Court struck down the Johnson insanity. Congratulations for having some sanity left in your country. Is Parliament back in session?

Oh, I see it is. At least, Guardian has it streaming live.

@FaheemMitha yes they restarted this morning but whether they can do much other than argue that what they did before was wrong, it remains to be seen

@DavidCarlisle Anyway, congratulations on getting this far.

These days, one should treasure each small victory of sanity.

@FaheemMitha Yes, but no PMQ, as Johnson is in New York.

@FaheemMitha Yes, Bercow.

@PauloCereda PMQ?

@PauloCereda No, because they have to have 3 days notice

3:36 PM

@PauloCereda no he's back

@FaheemMitha Prime Minister's Questions

@JosephWright oh

@DavidCarlisle oh no

I heard the Attorney General speaking earlier today.

@PauloCereda Ah, ok.

I think he's on the way back.

Someone should push him out of the plane, somewhere over the Atlantic.

3:52 PM

@FaheemMitha I've just installed Mercurial (to do a pull request for something) :)

@JosephWright bah

@PauloCereda It's an important PR

@JosephWright ooh beamer

@JosephWright Oh? What's the something?

@FaheemMitha filehook

@PauloCereda At one remove, yes: beamer loads it

4:11 PM

@JosephWright Oh. A LaTeX package.

@JosephWright :)

I see no reaction to my request for comments on this question: chat.stackexchange.com/transcript/message/51831146#51831146 Does anyone have any objection to opening the closed question therein for the reason of changing "unclear" to "duplicate"?

@FaheemMitha Well yes

@barbarabeeton After work

@FaheemMitha bitbucket.org/martin_scharrer/filehook/src/default

user image

for you guys

:-)

4:30 PM

@JosephWright Is that Mercurial? I can't tell.

@FaheemMitha Yes, Mercurial

@JosephWright It's hard to tell.

@JosephWright Martin repos. :)

4:49 PM

twitter.com/TeXtip has 41k followers!

@JosephWright let's counterattack

@PauloCereda Working on it ;)

@PauloCereda More than Overleaf

@JosephWright soon L3 will overtake these numbers

@JosephWright (dibs on shared account management)

It's kind of soothing to listen to people speaking actual English. And I think Bercow could do standup.

And it seems they are all friends, and all honourable. It's so heartwarming.

5:29 PM

Wow, This is impressive: c82.net/euclid.

@PeterGrill I think someone posted that a while back. I think the source is available on GitHub or somewhere like that.

As I recall, I was amazed that anyone had the time. But hobby, apparently.

Stefan Kottwitz

@JosephWright @kkinkytoys follows @textip

@StefanKottwitz I never said 41k sensible followers!

Stefan Kottwitz

@JosephWright It's sensible! ok, from UK :-)

Just joking, I like UK based companies

what a pity that free travel and no customs may end, but perhaps not, we will see, not raising talk about

6:02 PM

@egreg twitter.com/mathforge/status/1176896131860750336?s=09

6:17 PM

5

Q: How to have hashes doubled _and_ things expanded?

I'd like to learn some TeX programming technique which I can always apply for handling the same type of situation: The code \newtoks\mytokenregister \def\five{\four5} \def\four{\three4} \def\three{\two3} \def\two{\one2} \def\one{1} \def\tokenstomacro#1{% \mytokenregister{#1}% \edef\macro{\t...

macros expansion arguments

I wonder if a question about \expanded is a good plan ...

7:00 PM

@JosephWright you could ask "who added \expanded to all the texlive2019 engines?`

@DavidCarlisle :)

@JosephWright the PM is on!

@PauloCereda He's on something!

@JosephWright lost part of it. :(

7:16 PM

@JosephWright I'm sure my version is easier to read than \expanded :-)

7:31 PM

@DavidCarlisle Nice

7:51 PM

@DavidCarlisle Live and let die ;)

8:26 PM

@DavidCarlisle You going to summarise for BLF?

@JosephWright ? oh mail, not here, I see

@JosephWright OK

@DavidCarlisle Cool

@JosephWright but the workaround is already in the public -dev format isn't it?

@DavidCarlisle No, just the github

8:43 PM

@JosephWright then I'm confused, let me check something...

@JosephWright pr-3 is in tl isn't it (seems to work here) github.com/latex3/latex2e/issues/177#issuecomment-531470359

Is this a ok place to ask generic and philosophical questions about latex?

@Bob yes

Ok Great! My question is about when I should be using lua or expl3. For my personal projects I am writing my own .cls files. And on two separate occasions I have found the need to write programing like functions that took variable inputs. These inputs are then processed and used to fill out what otherwise would be a template.

I first made this work with expl3, because I found out about it first. Recently I made a very similar function using lua.

@DavidCarlisle PR-3 is, but that commit was after the dev release

It seems they both work just fine, but it was so much easier to code in lua than expl3. Why and when should I use expl3?

8:53 PM

@Bob Do you want to go LuaTeX-only?

I dont know the consequences of saying yes to that question.

I have been using xelatex ever since I first dabbled in latex years ago, only for its support of unicode characters. Having never had any issues with it, I never tried lualatex until a few weeks ago.

My document compiled just fine and I was none the wiser.

@Bob Sure

@Bob pdfTeX has a stability level in terms of (lack of) change that LuaTeX will likely never match. For a lot of purposes, that's fine: you don't need the same page breaks in 20+ years from a document. But for people who do, LuaTeX is an issue.

Phelype Oleinik

Speaking pre-release issues: microtype expects a non-robust \showhyphens and redefines it that way... Should I (or someone else) mail the maintainer?

@Bob pdfTeX is also faster than LuaTeX: this is an issue for example for heavy users of automated systesm

I want to make sure my base understanding is correct.

TeX is a typesetting system, and Latex is akin to a macro set that resides above TeX?

9:01 PM

@Bob LaTeX is exactly that

Ok good. But what is the difference between say, XeTeX and XeLaTeX, or LuaTeX and LuaLaTeX?

@Bob Same thing: XeLaTeX is the LaTeX set of macros running on the XeTeX engine

@Bob LuaLaTeX is LaTeX macros on LuaTeX

@Bob At the LaTeX kernel level, there is relatively little difference in terms of functionality based on the engine (pdfTeX/XeTeX/LuaTeX): just some stuff that's really necessary to load

Ok. So then how does expl3 fit into this picture?

@Bob expl3 is the programming language that the LaTeX team have worked on since before LaTeX2e was released (!). It was started well before LuaTeX was around. The idea was and is to provide a set of tools to make TeX programming easier.

@Bob At present, expl3 is loadable as a LaTeX2e package, though the original aim was to write an entirely new LaTeX purely in expl3 (that's still in mind, though delivery of actual results means its tricky)

So it is not an engine like TeX is?

9:16 PM

@Bob Lua in LuaTeX doesn't negate the idea of expl3. First there is the fact that some stuff is better done at the macro layer even in LuaTeX. Then there is the business that for a lot of users, pdfTeX is fine and they want the stability it offers. (ConTeXt made a different judgement but with a much smaller user base)

@Bob No, it's a collection of TeX macros

Could you give me an example of something you would want to use expl3 over lua for?

At this time I have only tried to use them to create pseudo data structures

@Bob Well xparse would be a good example: its about defining document syntax parsing for LaTeX2e-like documents. That's all about grabbing tokens ...

And I found variable declaration and arrays to be very difficult to handle in expl3

@Bob For siunitx (my package for units), there is a lot of stuff at the typesetting end that is much easier tokenized

@Bob Don't follow on variable declarations; for arrays, there's really no beating a TeX csname-based approach for a macro programmer (\csname foo@1\endcsname, etc.)

@Bob expl3 is a set of tex macros designed for tex typesetting tasks, Lua is a general purpose programming language, so the intersection of tasks for which there is a choice is rather small, and also most (nearly all) public latex packages are designed to work with pdftex as well as luatex and xetex, and that means lua isn't an option

9:23 PM

@Bob It will depend on what you want to do: there's no question that Lua is better for data manipulation if you are prepared to rule out anyone using another engine

I will have to read up later, but in the mean time can you remind me what xparse does? My usage of it was hand in hand with expl3, and it was a few years ago, so I do not remember the boundary between the two.

@Bob it allows you to easily define latex syntax commands with * forms [] optional arguments etc

@Bob it is written in expl3 and also the "expected" use is that the actual body of the definition of the new command is written in expl3 code, and then xparse is used to just declare the top level user syntax

Yes ok that seems to be how I remember using it.

So expl3 is compatible with pdfTeX or xeTeX or LuaTeX because it builds entirely off Tex?

9:46 PM

@Bob Off (essentially) pdfTeX, yes

Were xeTeX and luaTeX branches of pdfTex?

@Bob Not really. TeX led to e-TeX, which led to pdfTeX. XeTeX was started from e-TeX. LuaTeX did originally start from pdfTeX but deliberately changed quite a lot of behaviour (subtly but in important places)

Ok i think I am starting to get a picture of how all the blocks go together.

10:07 PM

Just failed to avoid getting drawn into a why-don't-we-have-mathjax discussion on tex.meta.stackexchange.com/a/1273/86 I hope I've been polite, but I do think that the comments should go (I've flagged them).

However, with the exception of compatibility, I guess I still don't have a satisfying answer to my initial question as to when I should expl3 or lua as a form of best practice. I do suppose though that compatibility is certainly worth something when making public packages.

@Bob probably at some point in the future something not totally unlike luatex will be the dominant tex-like engine, so you using Lua now is probably not going to be a long term hindrance but currently pdftex is by far the most commonly used engine, but its sort of hard to justify an 8-bit system using mostly custom font formats and encodings in a global Unicode world, but things move slowly...

@LoopSpace you could use the starred response listed over on the right, if that would help:-)

@Bob well @JosephWright and I are perhaps not the best people to ask, ask we are on the latex team so need to maintain latex and expl3 and keep it compatible with all the major tex variants, so compatibility is somewhat more important to us than perhaps to a typical user..

It could just be me but coding in expl3 was completely unlike anything else I've done. It was very alien. Dealing with expansion made my brain hurt.

@Bob Compared with?

C and java

10:11 PM

@Bob with tex you can not avoid expansion but expl3 by design hides a lot from you, one of the main design aims is that it_ handles expansion and the user doesn't need to use chains of 15 \expandafter to make things work

@Bob As @DavidCarlisle says, we are likely not the best people to ask: I find Lua more tricky that TeX as I can't trace the expansion ;)

@DavidCarlisle Sort of what I tried ...

@Bob programming in tex is like programming in the C pre-processor, with no C compiler.

I find programming in expl3 easier than in pure tex, but harder than banging my head against a brick wall.

5

@Bob it is the same macro expansion paradigm (and of a similar era in terms of language design)

10:14 PM

Maybe the way I used lua was unconventional? My lua program was something like this.

15 or so getvariable setvariable commands
and one build command which which tex.prints{} a giant formatted string of latex-compatible code.

I just call the \buildcommand in my .tex and everything works fine and dandy.

This is essentially what I did with my expl3 code too.

@DavidCarlisle in particular what I remember was difficulty with :nNSNSCxjwsksowdnsksNAS

or whatever I had to type after each command to make it do what I wanted.

@Bob sure but it is much easier to control expansion by saying x (to expand the argument fully), than to use the tex primitives to do the same but (a) you need to understand tex expansion before doing either and (b) I have been using that syntax since 1992 so I am not the person to make an objective comparison.

ha ok fair

@Bob Like @DavidCarlisle says, there is simply no getting away from expansion if programming in TeX. Some years ago, there was someone how wanted us to find a way to write something like expl3 without needing to specify expansion in the function names. That simply wasn't workable.

@Bob that's one way but actually often such a process could be done with classic tex and doing the programming part outside and reading in the results to tex via a file, then you can use (and people do use) Lua or perl or python or whatever. the really novel feature of luatex is its close integration in callbacks, so you can use Lua to replace previously fixed code, ..

... so for example if you don't like the tex linebreaking algorithm there is a callback and you can (in principle) do the entire linebreaking in Lua.

Oh I see

Yes in my use case I hadn't really the need to do anything other than provide content in an expedient fashion to be typeset normally by TeX

I had actually forgotten but I wrote the first version of this program in regular latex, before I ported it to expl3

But I couldnt determine how to make basic (expandable with no finite length) or arrays. So that led me to having to create way more variables than I ever thought I would need so I never 'overflowed' so to speak.

10:29 PM

@Bob one notable feature that is handled in lua is the font loading, so if apple or google or microsoft come up with yet another vaguely incompatible emoji font format, in classic tex you are doomed, in xetex you would need to wait for harftbuzz library to support it and xetex to use that future version, or in luatex you can (hope that somebody) write a font loader that understands that format.

hmm interesting

@Bob We (team) have not wanted arrays of arbitrary tokens, at least not ones that couldn't easily be handled 'classically'.

Yes I remember fonts was what drove me to use xetex within the first 3 days of me learning to write in latex.

@Bob well tex doesn't really have arrays (or integers) so as Joseph said above, most "array" systems come down to defining one macro for each array entry, and hiding the macro names with a plausible array-like syntax.

yes thats what I was doing

10:32 PM

@Bob Again, depends on what stability you want: system fonts can change, TeX fonts much less so

For a super simple example of my problem, I had a command like this

`entry{1 a 3 z}` that could be called as many times as you want.
then you would call `\buildtable{}` and it would make a 4 column table with all the previously called entries.

@Bob different people have different priorities. If you are an English speaking mathematician and started using tex a couple of decades before xetex existed, then fonts are not so much of an issue, really. If you are typeseting indic languages then xetex (and not luatex) is still what you want to do and older mechanisms to try to force such things through pdftex really can't be justified these days.

This made making lots and lots of these tables very fast.

@Bob The thing with building tables is of course they are then not explicitly in your sources; I know it's popular, but there are reasons to be at least a little wary

Yes honestly I dont really have much need for xetex anymore. Its just that after I started using it I never stopped.

10:35 PM

@Bob why is that faster than using tabular syntax? did you need to specify the entries not in row order?

I had it alphabetize the order based on the left most column. But more than that it made it very human readable, and took up less space. It also meant that later on if i wanted to change the way the table looked, I just had to change the function (which is in a class) and not hundreds of tables across multiple documents.

@Bob sorting perhaps, not so much the styling, if you have \begin{mytable}a&b\\c&d\end{mytable} then again you can restyle them all just by defining mytable

@Bob The old question of whether a TeX document should do this at all: the Knuth position of course is that it's meant to be pure typesetting, with all such processing already done ...

Yes thats an interesting take on it. Knowing more now than I didn when I started, I could have possibly defined my own sections. You see it wasnt just a table (as I said that was a basic example) the \buildcommand would actually harvest a bunch of other variables and put together an entire minipage. Like a datasheet

@JosephWright I did not mean to imply that the data was not in my source.tex

Can you elaborate on what you mean by processing? And how you differentiate that from the typesetting?

@Bob as Joseph said there are many times you need to generate a tex table/page/whatever from more structured data that is what the R packages do all the time, take some structured R data object and dump it out as latex but that is essentially external to tex, tex just typesets the result.

10:44 PM

Ah I understand now

@Bob but there is no right or wrong or hard and fast rules, pgfplot is definitely towards the extreme end of doing computation within tex, whereas plain tex is at the extreme end of not even having auto incrementing counters for section headings, it's a broad church:-)

@DavidCarlisle I was going to point to the DEK position ;)

@DavidCarlisle One for you

32

Q: Duck, duck, gone!

Here is the (quite scary) Five little ducks song(it is not long): Five little ducks went out one day, over the hills and up away. Mother Duck said, "Quack Quack Quack Quack", but only four little ducks came back. Four little ducks went out one day, over the hills and up away. Mother Duck said, ...

code-golf string

@egreg shame about the last verse

@Bob Like @DavidCarlisle says, there is no 'right' answer to using Lua vs expl3 vs TeX primitives (there are people who Really don't like any pre-defined utility macros)

11:02 PM

@DavidCarlisle In a few months there will be six ducks to roast.

Well actually my latest lua program does use tikz!

Mostly this time it was for a way of getting around having to manually change a bunch of node values in what would otherwize be a copy-paste situation. But it also autocalculates some length of decorative draw commands based on how many lines a paragraph node has.

@egreg I won't tell @PauloCereda that you said that.

11:20 PM

Anyways, thanks @JosephWright and @DavidCarlisle for the discussion. It was helpful.

@Bob If you look at ConTeXt, which is Lua-only, they do most of the 'heavy lifting' in Lua but still have non-trivial macro stuff too

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