Make bin-script on-par with scala script

[felixmulder]

The scala script has a larger amount of sophistication than our current ./bin/dotr. Help text from scala script:

Usage: scala <options> [<script|class|object|jar> <arguments>]
   or  scala -help

All options to scalac (see scalac -help) are also allowed.

The first given argument other than options to scala designates
what to run.  Runnable targets are:

  - a file containing scala source
  - the name of a compiled class
  - a runnable jar file with a valid Main-Class attribute
  - or if no argument is given, the repl (interactive shell) is started

Options to scala which reach the java runtime:

 -Dname=prop  passed directly to java to set system properties
 -J<arg>      -J is stripped and <arg> passed to java as-is
 -nobootcp    do not put the scala jars on the boot classpath (slower)

Other startup options:

 -howtorun    what to run <script|object|jar|guess> (default: guess)
 -i <file>    preload <file> before starting the repl
 -e <string>  execute <string> as if entered in the repl
 -save        save the compiled script in a jar for future use
 -nc          no compilation daemon: do not use the fsc offline compiler

A file argument will be run as a scala script unless it contains only
self-contained compilation units (classes and objects) and exactly one
runnable main method.  In that case the file will be compiled and the
main method invoked.  This provides a bridge between scripts and standard
scala source.

When running a script or using -e, an already running compilation daemon
(fsc) is used, or a new one started on demand.  The -nc option can be
used to prevent this.

With that being said what we'd actually like to do is to have main command with sub commands - think git or go.

E.g. to compile you'd go:

$ ./bin/dotc compile <ARGS>

to launch an interactive repl you'd say:

$ ./bin/dotc repl

[Varunram]

@felixmulder Assuming this is still a novice issue, is the end goal to combine both dotc and dotr into simply dotc? I would love it if you'd provide more insight into this. Thanks!

[felixmulder]

It sort of is, but it's not really a pressing issue. We've decided to do the first releases without scripts.

That being said, the scripts are in need of some form of update. But, we're still considering how to package things. I'd hold off on this for a little while..

[SethTisue]

there is a SIP in this area: scala/improvement-proposals#46

even before the SIP is approved or not, scala-cli is already available and works well: https://scala-cli.virtuslab.org/scripting