Remove requirement for blank line before list

[cliffckerr]

Description

Currently, Quarto requires a blank line before a list for it to render properly (from the Markdown basics Quarto docs):

Note that unlike other Markdown renderers (notably Jupyter and GitHub), lists in Quarto require an entire blank line above the list. Otherwise the list will not be rendered in list form, rather it will all appear as normal text along a single line.

Specifically, this:

My list:
- Item 1
- Item 2

currently renders as

My List: - Item 1 - Item 2

instead of

My list:

• Item 1
• Item 2

My question is simply: can this limitation be removed? It creates a barrier to switch to Quarto from another system, and seems like it would hopefully be quick to fix and make Quarto consistent with the other widely used Markdown renderers mentioned. I struggle to imagine a scenario in which the user wouldn't want a list in this scenario (a list with no blank line before it), so I don't imagine it would be an issue to change the default behavior.

My particular use case is a website (specifically, software documentation) pulling in README files written for GitHub and Python Jupyter notebooks, neither of which have this requirement for lists.

(See also #6713 and #4650, although neither of those are quite the same as this.)

[mcanouil]

No, it cannot currently as it comes from Pandoc (and many Markdown parser)

Note that you are asking something that goes against nearly all (if not all) Markdown linters.

• https://github.com/markdownlint/markdownlint/blob/main/docs/RULES.md#md032---lists-should-be-surrounded-by-blank-lines

Since the syntax with empty will render exactly the same in GitHub and Notebooks, I would suggest to switch to the more robust syntax by adding an empty line before and after list.

[cliffckerr]

It seems like it is an option in Pandoc to allow lists without a preceding blank line with a built-in extension:

• https://pandoc.org/MANUAL.html#extension-lists_without_preceding_blankline

Extension: lists_without_preceding_blankline±
Allow a list to occur right after a paragraph, with no intervening blank space.

CommonMark explicitly allows a list without a preceding blank line:

• https://spec.commonmark.org/0.31.2/#lists

In CommonMark, a list can interrupt a paragraph. That is, no blank line is needed to separate a paragraph from a following list:

I know there is no universally agreed upon Markdown standard, but I personally feel CommonMark is a Markdown flavor that should be supported! Would it be possible to consider at least making this an option for Quarto, since it's supported by Pandoc? Or is there a way in Quarto for users to manually configure Pandoc for options like this?

[mcanouil]

From what I read in the past, it means the author of Pandoc added the option because of CommonMark, but still, that's not the default behaviour.

Since there is an extension, then you should be able already to do what you want in Quarto. (changing to Q&A as what you've asked is already possible)

---
format: html
from: markdown+lists_without_preceding_blankline
---

List:
- First item
- Second item

(not tested as I'm on mobile)

[mcanouil]

Additionally, the following are the format+extensions to get something closer to CommonMark, note that changing all this can have unexpected side effects.

• quarto-cli/src/format/markdown/format-markdown.ts

  Lines 64 to 72 in 7c8fd21

  	"markdown_strict",
  	"+raw_html",
  	"+all_symbols_escapable",
  	"+backtick_code_blocks",
  	"+fenced_code_blocks",
  	"+space_in_atx_header",
  	"+intraword_underscores",
  	"+lists_without_preceding_blankline",
  	"+shortcut_reference_links",

[cliffckerr]

Thanks for that suggestion -- sounds like we're close! Do you have any suggestions for how to make this work with a Jupyter notebook rather than a .qmd file? If I add

---
format: html
from: markdown+lists_without_preceding_blankline
---

to a Markdown cell in a Jupyter notebook, it renders as text. I would also much prefer a global config flag / setting for Quarto, since editing 50+ source files (whether to include this header, or modify my lists with the extra space) is exactly what I'm trying to avoid in the first place!

[mcanouil]

It works the same way for Jupyter Notebooks.

As all the options, they can be set at project level _quarto.yml.