Interesting syntax extensions project for Rust: http://t.co/bjwYTjPmcx (seems a little odd that macros are parsed outside-in though).
miniblog.
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I've seen markdown projects leverage link syntax for custom extensions, e.g. [click me](button://).
Markdown also supports embedded HTML. Perhaps you could add custom tags for extensions?
Wikipedia is overhauling its theme! https://diff.wikimedia.org/2020/09/23/wikipedia-is-getting-a-new-look-for-the-first-time-in-10-years-heres-why/
I have sometimes installed CSS tinkering extensions just to fix the line length on desktop, so I'm glad to hear that's getting fixed.
A critique of RISC design, and why CPUs end up with custom instructions: https://blackhole12.com/blog/risc-is-fundamentally-unscalable/
(RISC-V has explicit support for extensions, so I think it will be less of an issue there. The idea that webassembly will make programs more portable is interesting.)
