Is there an official place that documents Elm’s syntax? I imagine the names and structures from the compiler are a good start, but has that info been turned into a document format?
Related: How were the module names chosen for stil4m/elm-syntax? Are the names based off the compiler’s internal modules or some other place?
The official syntax guide is here: http://elm-lang.org/docs/syntax
It’s not like a EBNF grammar, but it will get you going. What are you doing that you need to parse Elm source? There may be a better solution if we know what problem you’re trying to solve at a higher level. 
Ah ha! That term led me to this page which seems to be along the lines of what I’ve been looking for (though this was not expressed in my question)
I’ve considered a few projects that would benefit from being able to effectively parse Elm source code, though nothing has really left the “idea” stage yet. I think the next step for each of those projects is learning about Elm’s syntax.
Now, if stil4m/elm-syntax closely adheres to “spec”, that should suffice for most of my projects for the time being (most of my imaginary projects would be web-based applications).
There’s an old(er) thread about Lesser-known syntax that has some useful pieces of information.
Have you see this package?
http://package.elm-lang.org/packages/Bogdanp/elm-ast/latest
I’ve played around with it and it mostly works but I found a few cases of valid code that it wouldn’t parse. So it’s not an exact replica of the real compiler’s parser.
Yes, that’s a really cool thread. It does have some neat tricks 
Nice, I had not! I’ll have to compare that package with elm-syntax.