Clojurians Log v2

ok hopefully we can discover a minimal repro

It seems to be something to do with the way SVG elements are being appended to an existing SVG element. I can only get the bug to manifest in the browser, not in a test, because the there's no way in the happy-dom environment to check if it's actually visible. I think I know how to fix it though.

Hooray, I managed to get a repro test case failing: https://github.com/chr15m/eucalypt/pull/9/files

Awesome!

Fixed. I linked to the games page from the main demo page now. If you update your snake demo in the squint playground to Eucalypt 0.0.8 it works.

What was the issue?

I wonder if it intended to use rswap! which is intended for recursive reactive atom swappage?

and by intended I mean slept walk to the piano and played the first few notes of a song it once heard on the radio

The issue was the SVG namespace handling. Basically the LLM's initial logic for deciding which namespace to use during createElementNS was broken. I replaced it with something leaner that doesn't require state outside the patcher.

👍 🙏

I must say it smells ok, but the taste...

According to LLM eucalypt isn't sedative for humans nor koalas 😅

Btw this open issue about the games page, is that still relevant? I couldn't find the games branch

Oh it's actually merged into main now. You can got to localhost:8000/games.html to see the bug.

Click a tab and then another tab and the buttons disappear or double up, depending on the order you click tabs.

I've been trying to understand the bug today but not getting very far.

I did manage to get a failing test case working though so that's progress: https://github.com/chr15m/eucalypt/actions/runs/18258701125/job/51983658743 https://github.com/chr15m/eucalypt/commit/b05b2ffa80221d73728a6c3c80439a25aa56b338

Ok I figured out why this bug is happening and it's really silly. The LLM used r/atom instead of a regular atom when setting up timers. So there's some deeply nested recursive re-rendering happening. So the bug is in the test really, however I did run it against real Reagent which handles it fine. So I need to figure out what to do there. But in the meantime I can upload the games page which now works.

I think it comes down to swap! in ClojureScript being atomic, whereas in Eucalypt the swap! is on a fake atom and so two of them run at the same time and overlap.

Because the second one is happening off a timer. 🤔

Actually Eucalypt defers swap! to the Squint implementation, and I think it's not atomic. So a swap! on a timer that causes a re-render breaks things if it's already in the middle of a render. I guess I'd have to implement some locking mechanism in the render loop. 😵‍💫

what do you mean with swap! in squint not being atomic?

CLJS's swap! is just the same as (reset! foo (f @foo)) . Since JS has no threads, this will always happen "atomically", since this code is synchronous

So this remark doesn't make sense. Squint's swap! is just as "atomic" as CLJS's. https://github.com/chr15m/eucalypt/commit/0ba0b9777ea1f84ce2fd7f1156447fcc64f6c614 Also the remark before it you can remove now

atoms in clojurescript are just mutable boxes, there is nothing special to them, no locking mechanisms whatsoever - because it is JS there are no threads and there is no locking. It's implemented in squint the same way

Ah yes true. Thanks, I have removed those two statements from the README.

There must be something else going on which is causing a re-render during the initial render. The problem went away when I changed from Eucalypt's r/atom to a regular atom in the timers in https://github.com/chr15m/eucalypt/blob/main/src/test/src/timers_and_buttons.test.cljs#L24. So Eucalypt is doing something to trigger a re-render when the timer atoms are created, which is different to Reagent. Maybe :ref is called too early. 🤔 I'll create a new failing test and see if I can get to the bottom of it.

I also realized in the Snake demo the "Game Over!" does not appear unless I force re-render, but clicking 'compile!' in the sandbox, or navigating between tabs in the demo page shows it up.

Is there also structuredEquals?

I wish. I guess if it existed the isEqual function wouldn't be needed.

I tried to use this once but was disappointed. I can't remember what the limitation was, I think it doesn't support the symbol type In the end I had to write my own recursive function

Ah ok so if there's a js/Symbol in there it might fail.