Should Metals work with plain Scala3 files directly in VSCode workspace? ...no build tool, like SBT, is used

[jockbert]

I'm trying out Metals for coding Scala 3 in VSCode. No build tool is used, so there is no project for Metals to import. Each Scala file is a separate stand-alone program that I run directly with scala command in terminal. like this:

$ scala day3.1.sc input3A.txt
... some output
$ scala --version
Scala code runner version 3.1.0 -- Copyright 2002-2021, LAMP/EPFL

However, Metals seems confused and complain about syntax that the scala command has no issues with. Further Metals also tries to download Ammonite 2.3.8-124-2da846d2 for scala 2.13.7 (!), but failed. In an effort to solve the problem, I have tried to specify runner.dialect = scala3 in the file .scalafmt.conf, as mentioned here, but it does not help. See screenshot for details:

What do I need to do in order to have a good experience trying out Scala 3 using Metals in VSCode? Besides problem with the Scala 3 syntax, Metals does not show any documentation for methods in standard lib. Documentation for my own code works fine though.

[ckipp01]

Hey @jockbert so keep in mind that Metals is interpreting your .sc files as Ammonite scripts, not just normal Scala files. Because it's doing that it's trying to download the correct version of Ammonite. Metals doesn't yet support Ammonite with Scala 3, so those won't work.

In order to get a better experience with Scala 3 I'd recommend either putting those in a project with a valid Scala 3 build, making them .scala instead of .sc if they can truly stand alone, or maybe even using https://scala-cli.virtuslab.org/ which then Metals could connect to for standalone scripts and support Scala 3.

[jockbert]

Thanks, renaming to from .sc to .scala seems to fix the issue with false Scala problems (red markings) in editor. It was just ignorance using the suffix .sc, since Ammonite is not even used for these files.