Tutorial: self-referential record destructuring · beginners

I'm currently walking through the tutorial, and reached the point where the tutorial describes destructured record, in which an optional field is assigned a default expression which references another field in the destructured record.

Thus we have a destructured record in which the default value for the optional description field references the value of the title field of the same record.

To test this out, I wrote a short program to use this record, but get an error message on run, which tells me that The #UserApp module does not expose anything by the name title.

app "records"
    packages { pf: "https://github.com/roc-lang/basic-cli/releases/download/0.7.1/Icc3xJoIixF3hCcfXrDwLCu4wQHtNdPyoJkEbkgIElA.tar.br" }
    imports [pf.Stdout]
    provides [main] to pf

main =
    Stdout.line (tableDesc { height: 10, width: 20 })

tableDesc =\{
        height,
        width,
        title ? "My Table",
        description ? Str.concat "A table called " title
    } -> Str.concat description " with dimensions \(Num.toStr width) x \(Num.toStr height)"

Am I missing something here? It would appear that the self-referential destructuring functionality is currently broken.

Brendan Hansknecht (Dec 31 2023 at 21:12):

Interesting. My gut feeling is it never worked (at least I don't recall ever seeing it working). Maybe the tutorial is ahead of the actual implementation there.

Ian McLerran (Dec 31 2023 at 21:17):

Thanks! If its true that the tutorial is ahead of the implementation, I'm curious what the workflow is for building the tutorial...

Brendan Hansknecht (Dec 31 2023 at 22:20):

I think the tutorial is all manually written currently without any compilation verification, but that could have changed since I last looked at that. Not really familiar with the code.

Elias Mulhall (Jan 01 2024 at 01:25):

I'm on my phone right now, but I dug into this a while ago and made a few GitHub issues

Anton (Jan 01 2024 at 09:57):

I've created some issues to test tutorial snippets on CI #6328 #6329.
#6328 is a good first issue :)

Ian McLerran (Jan 02 2024 at 02:33):

Michael Pfeifer (Jan 14 2024 at 20:32):

@Ian McLerran , I was looking for a first issue and took the first one that was unassigned: #6328. I started working on it and I only noticed that you are also working on it when I tried to find the origin of the issue. If you are still working on the issue, please let me know. Otherwise, I will open a pull request.

Ian McLerran (Jan 15 2024 at 23:33):

Michael Pfeifer go ahead, I'm finding that I have a lot to learn on Rust before I can easily dive into any issue. Its all yours!

Stream: beginners

Topic: Tutorial: self-referential record destructuring

Ian McLerran (Dec 31 2023 at 21:02):