For me, breaking from not just a 40-year-old history of mathematical typesetting but also from the American Mathematical Society recommendations is the dagger. Plus doubling work if you want to reuse what you wrote to render MathJax or KaTeX.
> $\alpha x$ is correct and $\alpha\beta$ is correct, but $\alphax$ is not.
Like you said, braces can be used so all of the following are valid: ${\alpha}x$, $\alpha{x}$ or the odd $\alpha{}x$.
AsciiMath (what my tool was inspired by) tries to be smart about this by parsing a/f(x) differently from a/x(f) and it looks like typst is making the same choose. I on the other hand opted to rather stay consistent. My reasoning is that the tool is fast enough, and I rarely (actually never) type my math expressions outside of an interactive experience where I can’t view the rendered result as I type, so I can spot my mistakes immediately (usually fixed by adding a space, or surrounding something with parens).
Then LaTeX is not complete. Macros don’t have to respect the grouping provided by curly braces in math mode, therefore you only have the illusion of control. Nobody in practice actually inspects the full package dependency chain needed to typeset a nontrivial document.
Here’s a proof of concept: https://tex.stackexchange.com/questions/748416/how-can-i-aut...
That said, Typst has many good things, like easy to write methods, which this new language should adopt.
- The use of space character to also act as the escape character (latex use backslash) [1]. Not only does it cause confusion, I have to now escape everything $F=ma$ become $ F = m a $ in typst. Complex math equations will be complex no matter what - why make simple equations harder to type to make it slightly easier to type complex ones.
- The lack of these grouping brackets (latex uses curly parenthesis).
What I want from my typesetting language is "typsetting completeness". While there might be sane defaults, I want to be able to control every decision made by the typesetter by escaping and grouping things as needed. If the language doesn't have these features, by definition, it is not complete.
[1] Latex also has to use space to act as ending delimiters. $\alpha x$ is correct and $\alpha\beta$ is correct, but $\alphax$ is not. But the solution to this is to allow $αx$ which some flavors of tex do.