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Mlem dev here - you can add a link to the post by tapping on the link button in the toolbar then tapping “Paste”. We’re aware that this isn’t ideal UI, and are improving it in the next update.

Mlem dev here! Lemmy has a custom “flavor” of Markdown that is distinct from other social media platforms. Open-source markdown parsers and renderers exist for popular flavors of Markdown (e.g GitHub-flavor), but not for Lemmy-flavor. Most Lemmy clients choose to use an existing GitHub-flavor parser that is close enough to Lemmy’s to be indistinguishable in most cases. Mlem uses swift-markdown-ui to render markdown, which uses cmark-gfm as its parser.

Lemmy’s spoiler format is unique to Lemmy-flavor markdown, so that’s one of the places where use of a third-party markdown parser is noticed by users. Other common parsing errors are _subscript and footnotes.

Adding spoiler support is not particularly easy, unfortunately. You can’t really apply spoiler-parsing logic on-top of another markdown parser - it has to be integrated into the parser itself. This is because the app needs to ignore spoiler markdown in certain situations, such as inside of a code block. The only good option is to write a custom markdown parser from scratch, or modify an existing markdown parser to support Lemmy’s markdown dialect. Both options can be difficult for developers for several reasons:

• cmark-gfm is written in C, which the developer of the Lemmy client may not be familiar with.
• If the app is using a third-party renderer, and not just a parser, that renderer also needs to be rewritten to support the new parsing logic.

This takes a significant amount of time for comparatively little value for users, so most client developers didn’t prioritise it.

In an upcoming Mlem version, we’re replacing our markdown parser renderer with a custom one that can render spoilers and subscripts, but we’ve got a way to go before we achieve full parity with Lemmy. If any developers of other apps are using cmark-gfm, you’re welcome to use our code from that repo under the terms of the licence.

Sorry this is kinda long, I hope this answers your question

Footnotes^[1] are also undocumented.

Yeah, it’s rather inconsistent. I opened an issue for it a while ago.

Mlem dev here. It shows strikethrough, but not superscript. Lemmy has got a unique dialect of Markdown - in the current version we’re using an open-source Github-dialect parser, which is close to Lemmy’s dialect but not perfect. In the next update we’ve written a custom parser that handles all of Lemmy’s Markdown elements, including superscript and spoilers.