Wolfgang Schuster (Sep 16 2022 at 19:57): Wolfgang Schuster (Sep 16 2022 at 19:57):I've been a huge fan of @Ian Mackenzie 's packages in Elm. I use a bunch of them for a space simulation thing I've been building and they've helped me to not mix numbers with different units (which there are lot of in space). Even more so with making sure things are scaled properly! So I started playing porting them to Roc. Not sure how far I'll get (there's a lot of work) but it's a fun way to learn Roc Screen-Shot-2022-09-16-at-2.56.56-PM.png
Wolfgang Schuster (Sep 16 2022 at 19:58):Currently taking the Breakout example app and wrapping values
Wolfgang Schuster (Sep 16 2022 at 21:40):I love that I can have Bounds and Rect implicitly convert from/to Rust f32 and a wrapped Roc Quantity F32 Pixels. Makes it so the platform gives and takes pixels.
jan kili (Sep 16 2022 at 22:49):This is satisfying :)
Wolfgang Schuster (Sep 17 2022 at 16:05):Trying to migrate the existing Rect to a shapes like those in elm-geometry and struggling with getting a Point3d to work. Some of it is definitely me trying to write Elm in Roc :sweat_smile:
Wolfgang Schuster (Sep 17 2022 at 16:09):Trying to figure out how to be able to set a Point3d a units coordinates := { x : a, y : a, z : a } in my Model. Wondering if I need to be more constrained with my a :thinking:
Brendan Hansknecht (Sep 17 2022 at 16:10):I mean. You might want Num a, but that shouldn't be an error
Brendan Hansknecht (Sep 17 2022 at 16:11):What error are you getting with that struct?
Wolfgang Schuster (Sep 17 2022 at 16:12):I keep getting thread '<unnamed>' panicked at 'called Result::unwrap() on an Err value: Erroneous', crates/compiler/mono/src/ir.rs:3228:18 when I have
Model : {
ballPosition : Point3d Pixels ScreenSpace,
}
Model : {
ballPosition : Point3d Pixels ScreenSpace,
}
init ...
{ ballPosition: Point3d.pixels
(width |> Quantity.scaleBy 0.5 |> Pixels.inPixels)
(height |> Quantity.scaleBy 0.4 |> Pixels.inPixels)
(0),
}
width |> Quantity.scaleBy 0.5 |> Pixels.inPixels and give an a, which I think should be an F32 in this case
Wolfgang Schuster (Sep 17 2022 at 16:15):Same error with ballPosition: Point3d.pixels 5.0f32 10.0f32 0.0f32, (trying to eliminate other causes)
Wolfgang Schuster (Sep 17 2022 at 16:16):Maybe I need to be defining Point3d in the Rust part of the platform?
Brendan Hansknecht (Sep 17 2022 at 16:21):Shouldn't point3d take 3 values, not 2? At least based on the definition
Brendan Hansknecht (Sep 17 2022 at 16:22):Also, not sure it will give you a better error, but make sure to try roc check if you hit compiler errors. It tends to give better errors and not crash.
Wolfgang Schuster (Sep 17 2022 at 16:25):Thanks @Brendan Hansknecht ! Running check found the issue. I'd only written imports [ pf.Point3d ] and not pf.Point3d.{Point3d} :face_palm:
Brendan Hansknecht (Sep 17 2022 at 16:28):Ah
Brendan Hansknecht (Sep 17 2022 at 16:28):Cool
Brendan Hansknecht (Sep 17 2022 at 16:28):Glad to help
Wolfgang Schuster (Sep 19 2022 at 19:53):I've found it easier to catch these simple mistakes by using http://eradman.com/entrproject/, running it like find ./examples/roc-geometry/**/*.roc | entr -s 'cargo run check examples/roc-geometry/breakout-2.roc'
Wolfgang Schuster (Sep 19 2022 at 21:05):I don't know what I did, but my branch https://github.com/wolfadex/roc/tree/wolfadex/roc-geometry just hangs when running cargo run check examples/roc-geometry/breakout-2.roc and cargo run run examples/roc-geometry/breakout-2.roc. Even inserting a bad value like carl = 5 * "steve" at the top doesn't get it to fail
Wolfgang Schuster (Sep 19 2022 at 21:35):I think it was a circular import. Vector3d imported Direection3d, which imported Vector3d (bad copy paste)
Brendan Hansknecht (Sep 19 2022 at 22:23):Can you file an issue with a minimal repro. Would be good to print a proper error on something like this.
Wolfgang Schuster (Sep 19 2022 at 22:24):Already did, should have linked it here, https://github.com/roc-lang/roc/issues/4075
Last updated: Jul 26 2025 at 12:14 UTC