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Scala Runners

Replaces the Scala distribution's runners: scala, scalac, scaladoc, and scalap.

These runners add highly convenient options, most notably:

  • easily run any Scala version (e.g. scalac -212)
  • easily add dependencies (e.g. scala -Ccom.lihaoyi::fastparse:2.2.2)

See scala-runner -help for the usage text (using scala -help will give you Scala's help usage text).

The runners are implemented as thin shell scripts around Coursier's cs launch.

Install/Upgrade

Homebrew

Install with brew install --HEAD dwijnand/formulas/scala-runners.

Upgrade with brew upgrade --fetch-HEAD dwijnand/formulas/scala-runners.

Fix after master->main branch rename:

brew update
brew uninstall scala-runners
rm -fr ~/Library/Caches/Homebrew/scala-runners--git/
brew install --HEAD scala-runners

Fallback

You may also use this oneliner to get the scala-runners in your current directory:

curl -sSLO https://github.com/dwijnand/scala-runners/archive/refs/heads/main.zip && unzip main.zip scala-runners-main/scala* && mv scala-runners-main/scala* . && rm -r scala-runners-main main.zip

Then you can run them as ./scala ... or move them into your PATH.

NOTE: The runner requires Coursier's cs be executable and on the PATH, and various options require hub and jq.

Example Usages

Open a Scala REPL

$ scala
Welcome to Scala 2.13.0 (OpenJDK GraalVM CE 19.0.0, Java 1.8.0_212).
Type in expressions for evaluation. Or try :help.

scala>

Run any basic Scala command-line tool

$ scala -version
Scala code runner version 2.13.2 -- Copyright 2002-2020, LAMP/EPFL and Lightbend, Inc.

$ scalac -version
Scala compiler version 2.13.2 -- Copyright 2002-2020, LAMP/EPFL and Lightbend, Inc.

$ scaladoc -version
Scaladoc version 2.13.2 -- Copyright 2002-2020, LAMP/EPFL and Lightbend, Inc.

$ scalap -version
Scala classfile decoder version 2.0.1 -- (c) 2002-2020 LAMP/EPFL

If no version is specified, the latest stable release is retrieved, cached, and used.

Specify the Scala version, using short-hand or the full version string

$ scalac -212 -version
Scala compiler version 2.12.11 -- Copyright 2002-2020, LAMP/EPFL and Lightbend, Inc.

$ scalac -210 -version
Scala compiler version 2.10.7 -- Copyright 2002-2017, LAMP/EPFL

$ scalac --scala-version 2.10.4 -version
Scala compiler version 2.10.4 -- Copyright 2002-2013, LAMP/EPFL

$ scalac -2.12.2 -version
Scala compiler version 2.12.2 -- Copyright 2002-2017, LAMP/EPFL and Lightbend, Inc.

Add a dependency in the REPL

$ scala -Ccom.lihaoyi::fastparse:2.2.2
Welcome to Scala 2.13.2 (Java HotSpot(TM) 64-Bit GraalVM EE 19.2.1, Java 1.8.0_231).
Type in expressions for evaluation. Or try :help.

scala> import fastparse._, NoWhitespace._
import fastparse._
import NoWhitespace._

For Scala-based dependencies, using :: appends the Scala binary version automatically. Use : for Java-based dependencies.

Pass runner specific options

$ scalac --scala-version 2.10.4 -X
Usage: scalac <options> <source files>

[...]
  -Xprint:<phases>               Print out program after <phases>
  -Xprint-icode[:phases]         Log internal icode to *.icode files after <phases> (default: icode)
  -Xprint-pos                    Print tree positions, as offsets.
  -Xprint-types                  Print tree types (debugging option).
[...]

$ scalac --scala-version 2.10.4 -Y
Usage: scalac <options> <source files>

[...]
  -Yshow:<phases>                     (Requires -Xshow-class or -Xshow-object) Show after <phases>
  -Yshow-symkinds                     Print abbreviated symbol kinds next to symbol names.
  -Yshow-syms                         Print the AST symbol hierarchy after each phase.
  -Yshow-trees                        (Requires -Xprint:) Print detailed ASTs in formatted form.
  -Yshow-trees-compact                (Requires -Xprint:) Print detailed ASTs in compact form.
  -Yshow-trees-stringified            (Requires -Xprint:) Print stringifications along with detailed ASTs.
[...]

Test a Scala nightly

For the most recent nightly which has been validated by the Scala community build:

$ scala -2.13.next
Welcome to Scala 2.13.3-bin-560e1c9 (OpenJDK 64-Bit Server VM, Java 1.8.0_252).
[...]

Or for the most recent nightly (the HEAD of the 2.13.x branch):

$ scala -2.13.head
Welcome to Scala 2.13.3-bin-2145995 (OpenJDK 64-Bit Server VM, Java 1.8.0_252).

For Scala 3 you should only give the major version as in 3.next and 3.head:

$ scala -3.head -version
Scala code runner version 3.0.3-RC1-bin-20210726-372930e-NIGHTLY-git-372930e -- Copyright 2002-2021, LAMP/EPFL

Test a Scala pull request

$ scala --scala-pr 8960
Welcome to Scala 2.13.3-20200505-220514-82445f1 (OpenJDK 64-Bit Server VM, Java 1.8.0_252).
Type in expressions for evaluation. Or try :help.
[...]

In this example, 8960 is the number of a pull request in the scala/scala repo and 82445f1 is the SHA of the last commit in the PR.

Getting the resolved Scala version

$ scala --print-scala-version
2.13.3
$ scala -212 --print-scala-version
2.12.12
$ scala -2.12.head --print-scala-version
2.12.13-bin-c30130b
$ scala --scala-pr 8936 --print-scala-version
2.12.12-bin-2424146-SNAPSHOT