Improve usage of uncover, only, etc., in math mode

[Holt59]

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Maybe I missed something, but usage of uncover, etc., in math mode seems kind of tricky, I tried the following:

# times is not directly available, need to go for #sym.times
$  x = 4 #uncover(2)[#sym.times (y + 5)] $

# needs to escape * and the * symbol is not the one from math mode (not vertically centered)
$ x = 4 #uncover(2)[\* (y + 5)] $

# does not work, compile error
$ uncover(2 *, y + 5) $

Ideally, one should be able to write math as if inside an equation when using uncover, etc.

[andreasKroepelin]

This looks like it is due to more general issues in Typst and its maths typesetting. What is the compile error in the last case?

[andreasKroepelin]

Can you take a look if this is fixed by using Typst 0.3.0? Because it did something with hide in maths mode.

[Holt59]

The error is still present with latest typst, the error in the last case is

error: panicked with: "you may only provide a single integer, an array of integers, or a string"
   ┌─ examples\slides.typ:82:13
   │
82 │         panic("you may only provide a single integer, an array of integers, or a string")
   │              ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

help: error occurred in this call of function `_check-visible`
    ┌─ examples\slides.typ:111:11
    │
111 │         if _check-visible(subslide.at(loc).first(), visible-subslides) {
    │            ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^  

[Enivex]

I've defined this myself as a workaround for now

#let only-math(visible-subslides, string) = {
    [#h(0cm)#_conditional-display(visible-subslides, false, "doesn't even matter", eval("$"+string+"$"))#h(0cm)]
}

(uncover can be modified similarly)

You can then write for instance #only-math(2,"F^(1\/2)") inside an equation. The #h(0cm)s are required to get correct spacing for some reason.