It's a disappointment or even failure of our current language scanning and parsing tools or, really, the way we used them, that this is not an easy exercise.
This way, simple lists can be specified via juxtaposition:
a b c
And then more complex lists
thing 1, thing 2, thing 3
and still more complex lists like
A complex thing; with data, and more data
can be specified in a way that is potentially still human-legible and easily editable.
Combined with ~instant feedback while typing and, ideally, a “brushing” system to allow selection of parts of the textual model via the linked drawing, I am hopeful that this can be solved resiliently, at least for the most common use cases.
(Part of why I am excited about OP’s work here though is that while I have done a fair bit in my own project on drawing a related kind of diagrams, I have myself only begun thinking about how to make the resulting drawings nicely stylable/themeable.)
[1] https://mstone.info/depict/ -> https://github.com/mstone/depict
The result is that it’s very challenging to type syntactically correct dot at “line-speed”, e.g., if one is taking notes.
(This is one of several reasons that I think there is definitely still room for improvement in notation for graph-drawing, as I have begun exploring in my own work.)