\intertext{...} from LaTeX to Typst

[joshniemela]

Currently, it isn't possible to convert aligned environments containing \intertext. Immediate solution: converting \intertext{...} to $...$ in Typst will give the intended result of intertext

Is this solution good enough or did I miss something?

[jgm]

The fundamental problem is that texmath's TeX reader doesn't yet support intertext. That should be added.

[joshniemela]

Is this perhaps something I could try to implement?

[jgm]

Maybe! First step would be figuring out how to represent intertext in our AST; second step would be implementing it in the parser (src/Text/TeXMath/Readers/TeX.hs)

This is how we currently represent aligned environments:

% texmath -t native
\begin{align}
x &= y \\
1 &= 2
\end{align}
^D
[ EArray
    [ AlignRight , AlignLeft ]
    [ [ [ EIdentifier "x" ] , [ ESymbol Rel "=" , EIdentifier "y" ] ]
    , [ [ ENumber "1" ] , [ ESymbol Rel "=" , ENumber "2" ] ]
    ]
]

As you can see, there's no dedicated construction for aligned equations (which is maybe a problem, see #209). We just use an array. This makes it hard to see how we'd support intertext.

[Enivex]

To me it seems natural that intertext would just split the equation environment into two parts. Sure the alignment would be off, but at least the text would be there. As in

\begin{align*}
    Math part 1
    \intertext{Some text}
    Math part 2}
\end{align*}

gets treated as

\begin{align*}
    Math part 1
\end{align*}
Some text
\begin{align*}
    Math part 2}
\end{align*}

[jgm]

@Enivex yes that's a good idea and it should be feasible.

[10decikelvin]

In the meantime, I've made a hacky solution based on the amazing work by @jorsn on this other github issue that somewhat implements the functionality of \intertext{}.

Demo

What this does

• Insert text between aligned equations
• Independently cite and label equations within a group of aligned equations

Known issues

• Doesn't work across page breaks (can't be fixed)
• Doesn't work for text longer than one line (can be fixed but very difficult)

This is only a temp fix, and I really hope the typst devs pay attention to this issue and fix it soon once and for all.