Conceal amsmath matrix environments

[kiryph]

This was part of the issue #2645.

Following amsmath matrix environments can be concealed by surrounding them with the corresponding character instead of \begin{type} and \end{type}.

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=)

[lervag]

I've added these now; please update and test. Let me know if you think something be wrong.

[kiryph]

Yes, there is something wrong: \end{\([VvBbp]|small\)matrix should show the closing conceal character.

[lervag]

Sorry, that was a silly mistake on my part. Should be fixed now.

[kiryph]

Yes, now it looks good. Thank you.

[lervag]

By the way, we could add \s* to these regexps as well (e.g. \\begin{x}\s*) - would that be desireable?

[kiryph]

By the way, we could add \s* to these regexps as well (e.g. \begin{x}\s*) - would that be desireable?

Here I am not sure. If someone wants to have it more compact, should be able to remove the whitespace physically.
I suppose you refer to my request to do this for \langle.
Here was my reasoning as following:
I usually use in math mode a space to terminate commands without args to be able to proceed with ordinary letters. I know for \langle A\rangle one could write also \langle{}A\rangle and \langle{} could be concealed as ⟨. I think what I have seen by others that, how I do it, is not uncommon.
So the addition of the space is somewhat necessary (to avoid inserting {}). But for \begin{} this is not the case. So adding here spaces could indicate that the author wants give the input a little bit of space and I would leave this untouched.

BTW, conceal \langle{} as ⟨ could be another concealment request 😄.

A General Note About Concealment in Matrices

The alignment of columns in math matrices can be/is messed up due to active concealment which can actually decrease readability (Is the correct term in the correct column?). But I suppose there is nothing what can be done to align concealed blocks according to &, \\ and the length of the concealed expression.

[lervag]

By the way, we could add \s* to these regexps as well (e.g. \begin{x}\s*) - would that be desireable?

Here I am not sure. If someone wants to have it more compact, should be able to remove the whitespace physically. I suppose you refer to my request to do this for \langle. Here was my reasoning as following: I usually use in math mode a space to terminate commands without args to be able to proceed with ordinary letters. I know for \langle A\rangle one could write also \langle{}A\rangle and \langle{} could be concealed as ⟨. I think what I have seen by others that, how I do it, is not uncommon. So the addition of the space is somewhat necessary (to avoid inserting {}).

You are right!

But for \begin{} this is not the case. So adding here spaces could indicate that the author wants give the input a little bit of space and I would leave this untouched.

Agreed!

BTW, conceal \langle{} as ⟨ could be another concealment request smile.

Hmm... why would anyone want to write that?

A General Note About Concealment in Matrices

The alignment of columns in math matrices can be/is messed up due to active concealment which can actually decrease readability (Is the correct term in the correct column?). But I suppose there is nothing what can be done to align concealed blocks according to &, \\ and the length of the concealed expression.

Yes, that is probably right, and no, I don't think we can do much about that. Sorry.

[kiryph]

Hmm... why would anyone want to write that?

I do not know. Not me.

[kiryph]

Regarding the issue with alignment in matrix environments when concealment is active:

Do not use concealment but use directly unicode characters, e.g. with https://ctan.org/pkg/unicode-math or https://ctan.org/pkg/unicode-math-input and a vim plugin to help entering unicode characters: https://github.com/joom/latex-unicoder.vim.

[lervag]

Yes, agreed, that would be a simple solution. At least conceptually!