Make cs setup include scala-cli

[bjornregnell]

(*) Edit + TLDR This issue started out by discussing how scala-cli and coursier should align installation and also discussed the gettingstarted experience and the official download instructions. The consensus seem to be that coursier's cs setup should include installation of scala-cli as a first step, before scala-cli eventually becomes the new official scala runner. (scroll down to the end and see conclusions)

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(Initial issue kick-off text:)

Is your feature request related to a problem? Please describe.
The current official Scala Getting-started-instructions are based on coursier, because cs can install stuff like sbt and what not. But scala-cli is more beginner-friendly and could replace cs as the official install method to make the getting-started experience even better.

Describe the solution you'd like
Enhance scala-cli with install abilities similar to cs so that scala-cli can install stuff like sbt, sbtn, scalac, scalafmt, and other useful stuff.

Additional context
scala-cli already wraps coursier under the hood so this should be a low-hanging-fruit if I have understood it correctly.

[bjornregnell]

This is one of the things pointed out by @julienrf as a step towards basing the official getting-started on scala cli.
#905

[ckipp01]

Enhance scala-cli with install abilities similar to cs so that scala-cli can install stuff like sbt, sbtn, scalac, scalafmt, and other useful stuff.

Just to add my two cents. I personally find this a bit odd that my build tool (scala-cli) would be installing other tools, like sbt or scalafmt. I personally wouldn't want this, but understand the desire to have something easier for people to get started on.

Ever since we created "Solidify Getting Started with Coursier" in here the goal was to ensure an easy start with coursier. Why is it not sufficient that cs setup just gives you scala-cli? By doing it the other way around we're also introducing all sorts of oddities and potential confusion where maybe you installed X with brew, maybe with cs, or maybe with scala-cli?

I sort of feel like we started to chase the idea of making coursier a solid way to get started, and are now considering just stopping and backing another horse to get started. I really love scala-cli, but I feel like coursier should install it, not the other way around where it installs my other tools. If there are issues with the current getting started experience with Coursier I'd be more in favor of making that as user friendly as possible because it already can install all the things I want and need to get started with Scala.

[romanowski]

I think there are 2 aspects here and I got a feeling that we mixing them up. So we have:

• scala-cli as a tool should allow to install things or be a frontend to coursier
• newcomers, after installing Scala should be able to easily install sbt, scalac etc.

I think scala-cli should not double what coursier offers but on the other hand, I think installing scala-cli (or scala in the future) run should also install couriser.

Coursier is amazing and the idea that it should be the entry point to Scala ecosystem is good however I think that a need to install another tool to install Scala will be confusing to newcomers - that is why we think this 'bundle install' is a way forward.

[ckipp01]

I think installing scala-cli (or scala in the future) run should also install couriser.

Sure, this makes sense.

[bjornregnell]

Thank you @ckipp01 for raising the need for clarification. Scala-cli and Coursier are both amazing tools and they benefit from each other, and my phrasing of the topic of this issue is perhaps a bit misleading as I meant to discuss how scala-cli can build on cs to do the things needed by a new-comer to Scala.

If a beginner should only install one thing to run their first Scala program then a runner is more important than an installer, so a one-click install would be great.

If scala-cli installs cs without any extra effort then professionals and beginners are both happy :)

This issue is a step towards making the official getting-started page suitable for both pure beginners and experienced professionals, which is not an easy job and requires careful thinking about various user types use cases...

[alexarchambault]

What do you all think about moving (or duplicating in a first time) the setup command of coursier in Scala CLI? That way, a typical beginner path should be something like

• install Scala CLI
• toy a bit with it on small projects
• if the user wants to works on bigger Scala projects, run scala-cli setup to properly install a JVM + sbt, scalafmt, … and cs.
• now cs is installed, it can update itself (although there are issues with that on Windows…, but there's a workaround: cs update coursier && coursier update cs) and update the other apps, but for Scala CLI.

The only minor issue I see with this is that scala-cli isn't managed by coursier, but by whichever way users installed it initially.

[bjornregnell]

What do you all think about moving (or duplicating in a first time) the setup command of coursier in Scala CLI?

I think that duplicating the cs setup capability in scala-cli seems like a great idea!

minor issue I see with this is that scala-cli isn't managed by coursier

So I would still have to do scala-cli update to update scala-cli but scala-cli will remind/notify me of new available versions of scala-cli (and cs?) and state in that message how to update?

Or could coursier detect that it didn't install scala-cli and explain that scala-cli should be updated manually using scala-cli update when updating the other stuff with coursier?

Perhaps the user's ability to "talk" to underlying coursier could be expanded, by also duplicating other useful commands like install and update? That might perhaps be a road towards a (partly) unified user experience?

[bjornregnell]

Anyway, any minor install quirks across scala-cli + cs is not so much a problem, and getting the setup capability would greatly simply my students lives as they move from scala-cli simple project, towards trying out a "real" build tool.

[julienrf]

@alexarchambault It is unclear to me how those two items below would work in this order:

• toy a bit with it on small projects

• if the user wants to works on bigger Scala projects, run scala-cli setup to properly install a JVM + sbt, scalafmt, … and cs.

How would scala-cli run work if there is no JVM? It would download and cache a JVM somewhere but that JVM would not be made available to other tools (such as sbt)? Then, the role of scala-cli setup would only be to make the JVM available (e.g., by setting JAVA_HOME), and to install the usual Scala command-line tools (sbt, scalafmt, etc.)?

• now cs is installed, it can update itself (although there are issues with that on Windows…, but there's a workaround: cs update coursier && coursier update cs) and update the other apps, but for Scala CLI.

I think if scala-cli can do setup it should also do install and update. Basically, scala-cli and cs would become a single tool, so, there would be no need to install cs when running scala-cli setup.

[adpi2]

The solution described by @alexarchambault seems a bit odd to me. It makes things easier for the Scala beginners, they only see scala-cli and they don't need to interact with anything else. But then if they want to discover more in the existing Scala ecosystem they need to install another thing, called cs, and use that thing to manage other tools like sbt and mill. So the path from beginner to intermediate level programmer is still quite tortuous.

It is also a bit confusing. Because it can be interpreted as: scala-cli is the getting started tool but then if I want to become expert I must setup my workspace, use cs and the tools made available by cs. I was writing some Scala but my environment was not yet "set up".

In order to make things equally good for beginners and experts, I think there are two ways forward, etiher 1 or 2.

1. The "one-click install" installs both cs and scala-cli

The "one-click install" installs cs and then uses cs to install scala-cli.
scala-cli is always managed by Coursier and can be updated by Coursier. There is no scala-cli setup.

It is clear for beginners and experts what the roles of cs and scala-cli are:

• cs is the Scala applications manager
• scala-cli is the main Scala runner

In all our documentations and tutorials (in docs.scala-lang.org, but also in the sbt and Mill websites or any other Scala related website) we can assume that cs is already installed and can safely be used to install sbt, mill...

2. Merge Coursier CLI into scala-cli

scala-cli is the main Scala runner and the Scala applications manager.
cs is deprecated.

In terms of usage that means we will add a dozen commands into scala-cli. It will looks like this:

$ scala-cli
Usage: /home/piquerez/.local/share/coursier/bin/.scala-cli.aux <COMMAND>
Scala CLI is a command-line tool to interact with the Scala language. It lets you compile, run, test, and package your Scala code.

Other commands:
  export                                    Export current project to sbt or Mill
  help                                      Print help message
  install completions, install-completions  Installs completions into your shell
  setup-ide                                 Generate a BSP file that you can import into your IDE
  shebang                                   Like `run`, but more handy from shebang scripts

Doctor commands:
  doctor  Print details about this application

Main commands:
  clean                  Clean the workspace
  compile                Compile Scala code
  fmt, format, scalafmt  Format Scala code
  console, repl          Fire-up a Scala REPL
  package                Compile and package Scala code
  publish
  run                    Compile and run Scala code.
  test                   Compile and test Scala code

Resolution commands:
  fetch    Transitively fetch the JARs of one or more dependencies or an application.
  resolve  Resolve and print the transitive dependencies of one or more dependencies or an application.

Application commands:
  install    Install an application from its descriptor.
  list       List all currently installed applications.
  setup      Setup a machine for Scala development.
  uninstall  Uninstall one or more applications.
  update     Update one or more applications.
  channel  Manage additional channels, used by coursier to resolve application descriptors.
  search   Search application names from known channels.
  bootstrap  Create a binary launcher from a dependency or an application descriptor.
  launch     Launch an application from a dependency or an application descriptor.

Miscellaneous commands:
  about    Print details about this application
  version  Print `scala-cli` version

See 'scala-cli <command> --help' to read about a specific subcommand. To see full help run 'scala-cli <command> --help-full'.
To run another Scala CLI version, specify it with '--cli-version' before any other argument, like 'scala-cli --cli-version <version> args'.