> I've always implicitly assumed that tables were just an implementation detail for templates, and assumed they were like objects. I think that might be why it never occurred to me to apply `len` on a template, and why a large program like news.arc never ran into this gap.
Ah, interesting! Here's some background that might help understand why having them act like tables might help. `len` wasn't the first function that I found didn't work with templates; it was just the simplest. I was working on adding teardown functionality to unit-test.arc, and I wanted to look at some of the suites that were created, to see if I was adding tests properly. As the templates end up pretty big (one suite with two tests is about 25 lines), and it was late at night, I figured I'd make it simple on myself, and just look at the keys of the template.
This had nothing to do with the desired "production" code, but only with REPL-hacking introspection.
I want to make them reasonably easy to REPL-hack with; whether they're actually tables or not I don't particularly care right now. The most important table functions are probably len, keys, vals, and maybe maptable/each.
Haha, that certainly works. It brings up the question of "what Arc internals should people need to know about?". I've never looked into Arc's tagged types until this issue.
My answer to that question has always been, "it depends." The anti-encapsulation ethos (homoiconicity, using lists where other languages may use objects, the entire compiler fitting in one file and being accessible front-and-center, etc.) means that there's always the ability to peel back another layer of the onion when it becomes relevant.
I think it's a documentation issue. I think I had to search the forums to find out about it when I was playing with JSON interop. Nowhere on the actual template page in the Arc documentation does it tell you this is a thing.
Some things I've only been able to figure out by studying the compiler or arc source code itself. Granted, that's illuminating, but it's also sometimes really annoying.
Indeed. It never occurred to me to write about this. Would you be interested in writing something up? I can help you wrestle with the documentation system if you like.
