Scala CLI mode in Scastie

[julienrf]

Description

Scastie is an online Scala playground that allows everyone to write, run, and share Scala programs from their web browser.

Currently, Scastie allows users to configure their programs by exposing its sbt build definition. Users can add dependencies and set compiler options, for instance. This approach has several drawbacks:

• the configuration of the program is separate from its code,
• in order to run a program locally, users have to download a zip file containing an sbt project definition, and then use sbt.

As an alternative, we would like to allow the users to configure their program via Scala CLI directives. This would solve the issues mentioned above: the configuration would be part of the source code (as magic comments), and copying the program content to a local file would be enough to execute it locally (with scala-cli run).

Corresponding issue: scalacenter/scastie#603

Expected Outcome

Scastie supports a Scala CLI mode where the program configuration is defined with standard Scala CLI directives.

More specifically:

• in the “settings” screen, users could choose between sbt (current), or Scala CLI mode
• the program compilation and execution (on the server-side) will be managed by Scala CLI
• a Metals language server instance (running on the server) will enable IDE features on the client-side
• the code editor (on the client-side) will properly highlight the syntax of Scala CLI directives

Supervisors

Julien Richard-Foy (julien.richard-foy@epfl.ch): Technical director of the Scala Center. Jędrzej Rochala (jrochala@virtuslab.com): Software engineer at VirtusLab.

[julienrf]

Taken by @Maeeen

[kubukoz]

Is this already available in Scastie? I don't see anything non-sbt-specific in the web version, and directives don't seem to work OOTB.

[rochala]

@kubukoz The implementation has been finished 3 weeks ago and the PR is waiting for the review. Hopefully it will be merged in January.

[kubukoz]

Thanks for the update!