Stream: beginners

Topic: RocGlue - how to debug failing asserts

Jared (Jan 26 2024 at 17:16):

I'm playing around with basic-webserver, and running glue-gen.sh results in some syntax errors (which I have a fix for) and some failing assertions (which get commented out in the basic-webserver repo).

Jared (Jan 26 2024 at 17:16):

Any tips on how to find out what the size_of those unions actually are, and how to fix the calculations?

Jared (Jan 26 2024 at 17:17):

assert_eq!() is apparently invalid to use in a top-level const, so I'm not sure where to go from there

Richard Feldman (Jan 26 2024 at 17:17):

@Folkert de Vries knows a trick for that, but I forget what it is

Jared (Jan 26 2024 at 17:19):

ah ok, I managed to put an assert_eq in server.rs run_server(), so I at least know what the number should be now

Folkert de Vries (Jan 26 2024 at 17:22):

Just assert with == works for some types, numbers mostly

Jared (Jan 26 2024 at 17:27):

So assert with == doesn't tell you what the number actually was, if the assertion fails

Jared (Jan 26 2024 at 17:38):

ok noob question: is there a way to do a debug log in roc code? RustGlue.roc is huge and I'd like to quickly introspect what's going on in the middle of it.

Brendan Hansknecht (Jan 26 2024 at 17:54):

dbg someValue

Brendan Hansknecht (Jan 26 2024 at 17:54):

That said, no idea if glue is wired up to support it.

Folkert de Vries (Jan 26 2024 at 17:56):

for the assert, you can make a type error by doing something like assert!([0; 42] == [0; YOUR_VALUE])

Jared (Jan 26 2024 at 18:06):

oh nice

Jared (Jan 26 2024 at 18:07):

hm yeah looks like roc glue doesn't show the dbgs

Folkert de Vries (Jan 26 2024 at 18:09):

they should be somewhere, but you may not get to see the stdout of that process

Luke Boswell (Jan 26 2024 at 20:05):

It would be really nice to fix this particular issue. That would mean we dont have to keep the glue for basic-webserver and basic-cli checked into the repo but can use the script to generate locally when doing platform dev.

Folkert de Vries (Jan 26 2024 at 21:31):

you mean remove/adjust the failing asserts?

Luke Boswell (Jan 26 2024 at 21:51):

The glue bugs that generate invalid rust for those platforms.

Last updated: Jul 26 2025 at 12:14 UTC