This is a normal sbt project, you can compile code with sbt compile
and run it
with sbt run
, sbt console
will start a Dotty REPL.
If compiling this example project fails, you probably have a global sbt plugin
that does not work with dotty, try to disable all plugins in
~/.sbt/1.0/plugins
and ~/.sbt/1.0
.
Dotty comes built-in with IDE support, to try it out see http://dotty.epfl.ch/docs/usage/ide-support.html
The fastest way to start a new Dotty project is to use one of the following templates:
You will need to make the following adjustments to your build:
addSbtPlugin("ch.epfl.lamp" % "sbt-dotty" % "0.3.3")
sbt.version=1.2.8
Older versions of sbt are not supported.
Any version number that starts with 0.
is automatically recognized as Dotty by
the sbt-dotty
plugin, you don't need to set up anything:
scalaVersion := "0.16.0-RC3"
If the latest release of Dotty is missing a bugfix or feature you need, you may
wish to use a nightly build. Look at the bottom of
https://repo1.maven.org/maven2/ch/epfl/lamp/dotty_0.16/ to find the version
number for the latest nightly build. Alternatively, you can set scalaVersion := dottyLatestNightlyBuild.get
to always use the latest nightly build of dotty.
When porting an existing project, it's a good idea to start out with the Scala 2
compatibility mode (note that this mode affects typechecking and thus may
prevent some valid Dotty code from compiling) by adding to your build.sbt
:
scalacOptions ++= { if (isDotty.value) Seq("-language:Scala2") else Nil }
Using the isDotty
setting ensures that this option will only be set when
compiling with Dotty.
A tool to port code from Scala 2.x to Dotty is currently in development at https://github.com/scalacenter/scalafix
If your build contains dependencies that have only been published for Scala 2.x, you may be able to get them to work on Dotty by replacing:
libraryDependencies += "a" %% "b" % "c"
by:
libraryDependencies += ("a" %% "b" % "c").withDottyCompat(scalaVersion.value)
This will have no effect when compiling with Scala 2.x, but when compiling with Dotty this will change the cross-version to a Scala 2.x one. This works because Dotty is currently retro-compatible with Scala 2.x.
Alternatively, to set this setting on all your dependencies, you can use:
libraryDependencies := libraryDependencies.value.map(_.withDottyCompat(scalaVersion.value))
Feel free to come chat with us on the Dotty gitter!