# \[Pitch\] Markdown List Delimiters

**URL:** <https://forums.swift.org/t/pitch-markdown-list-delimiters/79174>\
**Category:** Foundation\
**Tags:** foundation, attributedstring, markdown\
**Created:** [April 8, 2025, 10:08pm UTC](https://forums.swift.org/t/pitch-markdown-list-delimiters/79174 "2025-04-08T22:08:41Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![jmschonfeld](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/jmschonfeld/32/20922_2.png) [@jmschonfeld](https://forums.swift.org/u/jmschonfeld)\
**Post date:** [April 8, 2025, 10:08pm UTC](https://forums.swift.org/t/pitch-markdown-list-delimiters/79174/1 "2025-04-08T22:08:42Z")

</div>

Hi everyone! I have a new pitch below for a new `AttributedString` attribute that I'd like to populate during markdown parsing to provide what delimiter was used in markdown source for entries in a list so that a rendered view of the markdown can use an appropriate matching delimiter. Take a look and let me know if you have any thoughts!

* * *

# Markdown List Item Delimiters

- Proposal: SF-NNNN
- Authors: [Jeremy Schonfeld](https://github.com/jmschonfeld)
- Review Manager: TBD
- Status: **Pitch**

## Revision history

- **v1** Initial version

## Introduction/Motivation

The markdown spec supports two types of lists: bullet lists and ordered lists. In Foundation's API today, we refer to them as unordered and ordered lists respectively via `PresentationIntent.Kind.unorderedList`/`PresentationIntent.Kind.orderedList`. Every item in a list begins with a "list item marker". For ordered lists, the list item marker is an ordinal number followed by a "." (U+002E Full Stop) or ")" (U+0029 Right Parenthesis) delimiter character (ex. "1." or "2)"). For unordered lists, the list item marker is one of three possible characters: "-" (U+002D Hyphen-Minus), "+" (U+002B Plus Sign), or "\*" (U+002A Asterisk). Note that lists must use a consistent list marker for every item in the list.

Today, an ordered list item's ordinal number is exposed via Foundation's APIs via the `.listItem(ordinal: Int)` `PresentationIntent.Kind` case for Swift and the `ordinal` property on the `NSPresentationIntent` type for Objective-C. However, we do not currently expose which list item marker a parsed unordered list used or which delimiter follows the ordinal numbers in an ordered list. It's reasonable that some markdown rendering views may wish to render the produced `AttributedString`'s list using the same list item characters in the original source text (or a comparible symbol to the original item) in which case it is important that the produced `AttributedString` provides which list item marker was used to denote items in a list.

## Proposed solution and example

To solve this, we propose adding a new attributed string attribute that will expose the list item delimiter for the current list in the produced attributed string. The value of this attribute will be a "." or ")" for ordered lists and a "-", "+", or "\*" for unordered lists. Developers will be able to access this value like the following:

```swift
let attrStr = try AttributedString(markdown: /* ... some markdown string ... */)

for (intent, range) in attrStr.runs[\.presentationIntent] {
    guard let component = intent.components.last else { continue }
    
    switch component.kind {
    case .listItem(let ordinal):
        let isOrdered = intent.components[intent.components.count - 2] == .orderedList
        let listItemDelimiter = attrStr[range].listItemDelimiter
        // Process list item using isOrdered, ordinal, and listItemDelimiter...
    }
}

```

* * *

For a full detailed design and considered alternatives, check out the [full proposal in the swift-foundation repo PR](https://github.com/swiftlang/swift-foundation/pull/1244).

---

<div class="post-metadata">

**Author:** ![tinaliu](https://sea2.discourse-cdn.com/swift/user_avatar/forums.swift.org/tinaliu/32/20927_2.png) [@tinaliu](https://forums.swift.org/u/tinaliu)\
**Post date:** [May 2, 2025, 4:44pm UTC](https://forums.swift.org/t/pitch-markdown-list-delimiters/79174/2 "2025-05-02T16:44:17Z")

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Since it's a pretty straightforward addition I'm going to accept this as-is.