[RFC] Further concealments: math matrices & envs, alignment character, conceal first space after left delimiter word e.g. \langle

[kiryph]

I am evaluating the concealment feature how much I would conceal to increase the readability:

I am trying following:

1. Math matrices
2. Math environments \begin{equation|...} and end{equation|...}
3. Alignment character &
4. First space after left delimiter word e.g. \langle

" Amsmath Matrices
" \begin{Vmatrix|vmatrix|Bmatrix|bmatrix|matrix|pmatrix|smallmatrix} \end{...}
syntax match texCmdEnvM "\\begin{Vmatrix}"     contained conceal cchar=║
syntax match texCmdEnvM "\\end{Vmatrix}"       contained conceal cchar=║
syntax match texCmdEnvM "\\begin{vmatrix}"     contained conceal cchar=|
syntax match texCmdEnvM "\\end{vmatrix}"       contained conceal cchar=|
syntax match texCmdEnvM "\\begin{Bmatrix}"     contained conceal cchar={
syntax match texCmdEnvM "\\end{Bmatrix}"       contained conceal cchar=}
syntax match texCmdEnvM "\\begin{bmatrix}"     contained conceal cchar=[
syntax match texCmdEnvM "\\end{bmatrix}"       contained conceal cchar=]
syntax match texCmdEnvM "\\begin{pmatrix}"     contained conceal cchar=(
syntax match texCmdEnvM "\\end{pmatrix}"       contained conceal cchar=)
syntax match texCmdEnvM "\\begin{smallmatrix}" contained conceal cchar=(
syntax match texCmdEnvM "\\end{smallmatrix}"   contained conceal cchar=)
syntax match texCmdEnvM "\\begin{matrix}"      contained conceal
syntax match texCmdEnvM "\\end{matrix}"        contained conceal

" Hide Array
syntax match texMathCmdEnv "\\begin{array}{.\{-}}" contained conceal
syntax match texMathCmdEnv "\\end{array}"          contained conceal

" Hide math environments similar to \[ \]
syntax match texMathEnvBgnEnd "\\begin{equation\*\?}" contained conceal
syntax match texMathEnvBgnEnd "\\end{equation\*\?}"   contained conceal
syntax match texMathEnvBgnEnd "\\begin{align\*\?}"    contained conceal
syntax match texMathEnvBgnEnd "\\end{align\*\?}"      contained conceal
syntax match texMathEnvBgnEnd "\\begin{gather\*\?}"   contained conceal
syntax match texMathEnvBgnEnd "\\end{gather\*\?}"     contained conceal
syntax match texMathEnvBgnEnd "\\begin{aligned\*\?}"  contained conceal
syntax match texMathEnvBgnEnd "\\end{aligned\*\?}"    contained conceal

syntax match texCmdEnvM "\\begin{alignat\*\?}{.\{-}}" contained conceal
syntax match texCmdEnvM "\\end{alignat\*\?}"          contained conceal

syntax match texCmdEnvM "\\begin{empheq\*\?}\(\[.\{-}\]\)\?{.\{-}}" contained conceal
syntax match texCmdEnvM "\\end{empheq\*\?}"                         contained conceal

" Conceal alignment character
syntax match texTabularChar /&/ conceal
syntax match texTabularChar /&/ contained conceal

For the math enviornments and the alignment character I feel like this should be optional and possibly by default turned off.

Currently, only the concealment for sections as markdown/atx formatting is disabled:

vimtex/doc/vimtex.txt

Lines 2410 to 2424 in b527d75

	let g:vimtex_syntax_conceal = {
	\ 'accents': 1,
	\ 'ligatures': 1,
	\ 'cites': 1,
	\ 'fancy': 1,
	\ 'spacing': 1,
	\ 'greek': 1,
	\ 'math_bounds': 1,
	\ 'math_delimiters': 1,
	\ 'math_fracs': 1,
	\ 'math_super_sub': 1,
	\ 'math_symbols': 1,
	\ 'sections': 0,
	\ 'styles': 1,
	\}

I also have refined the concealment of \langle as following:

" Refined concealment: capture optional space " \?"
syntax match texMathDelim "\\langle\> \?" contained conceal cchar=⟨

To understand the motivation consider this part of an equation:

\forall \{i,j;n_k\} \in E(\langle G,n\rangle)

is now displayed as

and without the refinement it looks like following:

Do you see the additional space after 〈 ?

I am not sure about them yet. I guess time will tell. If others consider them also worthwhile, they could express their interest.

[kiryph]

And also \{ and \} could be concealed:

syntax match texMathDelim contained conceal cchar={ "\\{"
syntax match texMathDelim contained conceal cchar=} "\\}"

[lervag]

Sorry, but I'm a little bit confused as to what you are proposing here. It seems to be several different things (all though all of them related to conceals). I'll start by addressing what I understand:

I also have refined the concealment of \langle as following:

I agree this makes sense. Perhaps one could do symmetrical it like this?

  syntax match texMathDelim contained conceal cchar=⟨ '\\langle\>\s*'
  syntax match texMathDelim contained conceal cchar=⟩ '\s*\\rangle\>'

If we add this, then I think it should be done for all variants similarly.

And also \{ and \} could be concealed:

syntax match texMathDelim contained conceal cchar={ "\\{"
syntax match texMathDelim contained conceal cchar=} "\\}"

Yes, I agree; I'm adding that now.

---

Now, for the first part, it seems you are suggesting new conceals of math related stuff. I think it would be easier to discuss them if they are raised as separated suggestions. But OK:

• Math matrices

This seems relevant and I could consider adding that. I think they should be optional, perhaps opt-in?

• Math environments \begin{equation|...} and end{equation|...}

I don't really like this; but, as mentioned elsewhere, I don't use conceals, and perhaps people who use them would find this useful..? At least, it should be opt-in.

• Alignment character &

This feels as something that might make things confusing, so I'm again a little bit skeptical.

[kiryph]

Sorry for not splitting it into different issues. I didn't want to spam you today. But I guess you would have prefered it in different issues. I will do this the next time. Since you already started answering each point, I will proceed here:

1. Math matrices: the safe set should be with visible characters

   syntax match texCmdEnvM "\\begin{Vmatrix}"     contained conceal cchar=║
   syntax match texCmdEnvM "\\end{Vmatrix}"       contained conceal cchar=║
   syntax match texCmdEnvM "\\begin{vmatrix}"     contained conceal cchar=|
   syntax match texCmdEnvM "\\end{vmatrix}"       contained conceal cchar=|
   syntax match texCmdEnvM "\\begin{Bmatrix}"     contained conceal cchar={
   syntax match texCmdEnvM "\\end{Bmatrix}"       contained conceal cchar=}
   syntax match texCmdEnvM "\\begin{bmatrix}"     contained conceal cchar=[
   syntax match texCmdEnvM "\\end{bmatrix}"       contained conceal cchar=]
   syntax match texCmdEnvM "\\begin{pmatrix}"     contained conceal cchar=(
   syntax match texCmdEnvM "\\end{pmatrix}"       contained conceal cchar=)
   syntax match texCmdEnvM "\\begin{smallmatrix}" contained conceal cchar=(
   syntax match texCmdEnvM "\\end{smallmatrix}"   contained conceal cchar=)

   I am not sure whether matrix and array is desired by everyone (since they simply vanish).

2. Math environments. I am actually not sure myself. I have a vim-unimpaired style toggle yoe to quickly disable concealment. I think one can leave this until someone else is interested (or only by default off). I have it for now in the personal after/ftplugin/tex.vim file.

3. Alignment character & Again, I agree this can be confusing. This can be done in a personal configuration as well.

4. I also have refined the concealment of \langle

   Perhaps one could do symmetrical it like this?

   I like this and yes doing it for all similar delimiters would also be the proper way.

5. \{ \} thanks for adding them

Here two screenshots of

\paragraph{Modulus of the position vector}
\begin{align*}
  \|\vec{r}\|^2  &= (x, y, z) \mat{G} \begin{pmatrix} x \\ y \\ z \\ \end{pmatrix} \\
    &= x^2 g_{11} + y^2 g_{22} + z^2 g_{33} + 2yz g_{23} + 2xz g_{13} + 2xy g_{12} \qquad\text{(3D)} \\
    &= x^2 g_{11} + y^2 g_{22} + 2xy g_{12} \qquad\text{(2D)}
\end{align*}

which illustrate many concealments including the discussed pmatrix, math env align and the alignment character &.

[lervag]

Sorry for not splitting it into different issues. I didn't want to spam you today. But I guess you would have prefered it in different issues. I will do this the next time.

Thanks; yes, I actually do prefer multiple small issues. It makes it easier to work fast on a single item, as I don't need to work through a lot of unrelated content (or, perhaps not unrelated, but, you know what I mean).

---

1. Math matrices: the safe set should be with visible characters … I am not sure whether matrix and array is desired by everyone (since they simply vanish).

Yes, I agree. Are these envs all from amsmath; i.e., should this be added to amsmath.vim?

---

2. Math environments. I am actually not sure myself. I have a vim-unimpaired style toggle yoe to quickly disable concealment. I think one can leave this until someone else is interested (or only by default off). I have it for now in the personal after/ftplugin/tex.vim file.

3. Alignment character & Again, I agree this can be confusing. This can be done in a personal configuration as well.

I think I'll leave these unless someone else should enter the discussion and express that they want them/one of them.

The alignment character is understandable with your screenshots. I can see how concealing them in align environments and similar makes sense. However, I would find it confusing if they were concealed in a tabular environment or similar. Thus, it seems safer to let you add this as a personal adjustment and to err on the cautious side here.

---

4. I also have refined the concealment of \langle
   > Perhaps one could do symmetrical it like this?
   I like this and yes doing it for all similar delimiters would also be the proper way.

Sounds good. I'll get on it when I have the time.

---

5. \{ \} thanks for adding them

My pleasure!

Here two screenshots of …

Thanks! It is nice to see an example of how this looks!

[lervag]

I've updated the delimiter conceals (ref. the \langle); please update and let me know if I missed something. It looks good to me on the limited testing I did.

[kiryph]

I've updated the delimiter conceals (ref. the \langle); please update and let me know if I missed something. It looks good to me on the limited testing I did.

Thanks. Right now, I do not have a document myself with all types. But at least for \langle it works as expected. I will let you know if I encounter issues.

I have created now separate issues for the remaining concealment questions on my side and close this.

[lervag]

Great, and thanks; I'll look into the issues one at a time as soon as I have the time.