> I just wrote a thin wrapper around the somewhat verbose JS Canvas API that lets me write code such as

As I said at the start of OP, I want to draw by doodling. So writing code would seem to be disqualified.

> Why use a new format instead of SVG or JS+canvas? It avoids reinventing the wheel and a webbrower is installed on almost every computer with a display.

My goal is to move off browsers. Reinventing the wheel can also often be a good thing.

I do have tools to export documents to html/markdown/SVG: https://git.sr.ht/~akkartik/lines2.love#associated-tools But I myself am trying to live outside the browser as much as possible.

I wasn't aware of Markdeep when I built this, but looking at it now, it's 6k+ lines of code: https://casual-effects.com/markdeep/latest/markdeep.js And then you need a browser underneath that weighs in at multiple GB (a scale that transcends lines of code metrics) By comparison, lines.love contains 2.6k LoC, and underneath it is LÖVE containing 100k LoC. This sort of analysis of the total size of the software supply chain and total hackability of the entire stack is what motivates me to look past web browsers. Once they grow past a certain size there is zero value to being open source for 99.99% of people.

(I do love that Markdeep is a single file of js without the ubiquitous pox of 1k-line package-lock.json!)

> Why use a new format instead of SVG or JS+canvas?

Because those are both hellaciously complex, and implementing a usable fraction of the functionality of either is not a job for a single hobbyist programmer. At least, I don’t think they are — I could be wrong. Even if I am, the number of programmers who can write code to draw a line given a JSON description has to be orders of magnitude of orders of magnitude larger than the number who can write an XML parser, an SVG implementation, a Javascript parser and runtime or a canvas implementation.

Any sufficiently complicated C or Fortran program…