typst / typst/codex

Invisible operators

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proposal
Dominant language
Rust
Stars
53
Forks
22
PR merge metrics
No merged PRs in 30d

Description

Context

Unicode defines multiple invisible operators, which are meant to disambiguate juxtaposition in mathematical text. This is primarily destined to be used by symbolic calculation softwares and screen readers. Their use is not mandatory but recommended to improve accessibility.

Invisible operators are the topic of section 2.14 of UTR #25 (the Technical Report on Unicode Support for Mathematics), and section 22.6 of the more recent, and authoritative Unicode 16.0.0 Core Specification.

Invisible operators were previously mentioned in https://github.com/typst/typst/issues/721#issuecomment-2351122402.

Formal proposal

Add the symbol variants from the following table under sym.

Character Name
U+2061 FUNCTION APPLICATION (Binary) ???[^1]
U+2062 INVISIBLE TIMES (Binary) times.invisible
U+2063 INVISIBLE SEPARATOR (Punctuation) comma.invisible[^2]
U+2024 INVISIBL PLUS (Special) plus.invisible

[^1]: TODO: Find a name.
[^2]: U+2063 has the Unicode informative alias "invisible comma."

Alternative names

Other possible names include invisible.{application,times,comma,plus}.

Concerns

Invisible operators seem to not be handled properly by the default math font.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

The issue names no source files, tests, or entry points; start by locating the sym symbol definitions in the repository and review sections 2.14 of UTR #25 and 22.6 of the Unicode 16.0.0 Core Specification. Done means the four proposed invisible operators have documented names and symbol variants under sym, with the default math-font concern checked.

Written by the indexing model from the issue text.

Assessment

Tech stack
rust
Domain
content
Issue type
Feature
Difficulty
3/5
Estimated time
1-2 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
38/100

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