Is there still difference between `$upright(…)$` and `$"…"$` in v0.14.0?

Questions
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1

In Typst v0.13.1, $upright(…)$ always use the math font, and $"…"$ may use another font.

#show math.equation: set text(font: (
  // To make the effect obvious, use a font that is absolutely unsuitable for math
  (name: "Fira Code", covers: regex("x")),
  "New Computer Modern Math",
))

$ x != upright(x) != "x" = #[x] $

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In Typst v0.14.0, the upright(x) above changes from New Computer Modern (Math) to Fira Code, so it becomes visually the same as "x" and #[x].

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So, is there still difference between $upright(…)$ and $"…"$ in Typst v0.14.0?

(I’m just curious, and don’t really want them in different fonts.)

Links

I encountered this problem while I was trying to document how to properly set font for non-English texts in equations: Document new features about math fonts by YDX-2147483647 · Pull Request #7118 · typst/typst · GitHub and PR#95 in Typst Chinese FAQ.

Previous discussion when it was still v0.13.1: What is the designed behaviour of font `covers` in math equations?

The PR that improved the situation: https://github.com/typst/typst/pull/6365

An old discussion that dates back to 2023: Text in math mode should use text font · Issue #366 · typst/typst · GitHub

1 Like
2

The difference is in how they are laid out internally at the moment. upright(x) will stay “inside” math layout, whereas "x" will be laid out externally. In particular, that means "x" goes through the normal text layout code. You should probably be able to find a situation where this difference is actually visible, but I can’t think of one at the moment.

Regardless, the intention is that “…” would use the text font in the future. So I think you should still use upright(x) if x is a variable (or something), and only do "x" if the x is actually text.

1 Like
3

Thanks for your explanation!

I can’t come up with any visually distinguishable example either, but I’m able verify your claim with yaml.encode($…$).
As shown in the table below, "x" and #[x] are texts, but upright(x) is a styled symbol (it.func() does not equal to std.symbol, however).

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Code 
#show math.equation: set text(font: (
  // To make the effect obvious, use a font that is absolutely unsuitable for math
  (name: "Libertinus Serif", covers: regex("[x]")),
  "New Computer Modern Math",
))

#let debug(content) = raw(yaml.encode(content), lang: "yaml")

#set page(height: auto, width: auto)
#set raw(lang: "typm")

#table(
  columns: 2,
  inset: 1em,
  align: (center + horizon, start),
  `x`, debug($x$),
  `upright(x)`, debug($upright(x)$),
  `"x"`, debug($"x"$),
  `#[x]`, debug($#[x]$),
)