Andy Hamon (Jan 06 2024 at 09:27): Andy Hamon (Jan 06 2024 at 09:27):I was trying to follow along with the record builder example and noticed an ID type used. At first I thought this was some made up type alias, but then I plugged it in to my roc repl and it seems to be built in.
I can't find any mention in the docs, so I'm wondering, what is ID?
mkrieger1 (Jan 06 2024 at 10:06):It's a made up tag I guess
Anton (Jan 06 2024 at 10:08):Yes, tags don't need some earlier definition, you can create them on the spot.
mkrieger1 (Jan 06 2024 at 10:09):Although I must admit that I also don't understand what := (ID, state) means in the example
mkrieger1 (Jan 06 2024 at 10:12):Since usually I thought that on the right hand side of a type definition there are other types or type variables, but as far as I know a tag is a value, not a type.
mkrieger1 (Jan 06 2024 at 10:14):And if ID were a tag with a payload state the comma confuses me.
Anton (Jan 06 2024 at 10:14):Good observation, I've looked at the full code and ID is actually an alias for a U32.
I'll improve the example
Anton (Jan 06 2024 at 10:15):So (ID, state) is actually a tuple of U32 and the type variable state that was passed to IDCount
mkrieger1 (Jan 06 2024 at 10:22):However, if I enter IDCount state := (MyID, state) in the REPL, it still accepts it. What is MyID now?
Anton (Jan 06 2024 at 10:23):Then it would be a tag
Andy Hamon (Jan 06 2024 at 10:32):Yep, came here to report back that I got fooled by a tag :smiling_face_with_tear:
Andy Hamon (Jan 06 2024 at 10:35):I've looked at the full code and ID is actually an alias for a U32.
I'll improve the example
Do you have a link to where you are looking?
Anton (Jan 06 2024 at 10:36):Yes :)
Notification Bot (Jan 08 2024 at 20:17):Andy Hamon has marked this topic as resolved.
Last updated: Jul 26 2025 at 12:14 UTC