I have started working with Actors, and was following a simple example as mention in the Getting Started Guide.
Specs:
Scala Version: 2.9.2
Akka Version: 2.0
I ran the example and it ran well. Then I changed by sbt build script to:
name := "PracAkka"
scalaVersion := "2.9.2"
resolvers += "Typesafe Repository" at "http://repo.typesafe.com/typesafe/releases/"
libraryDependencies += "com.typesafe.akka" % "akka-actor_2.10" % "2.1.2"
i.e. I started using Akka 2.1.2. There were small changes and as per the migration guide, I made the respective changes. But still I am getting the below error:
class file needed by Props is missing. reference type ClassTag of package reflect refers to nonexisting symbol.
What do I need to change?
The documentation is quite clear I'd say: http://doc.akka.io/docs/akka/2.1.2/project/migration-guide-2.0.x-2.1.x.html
(I.e. Akka 2.1.x is for Scala 2.10)
From the sbt documentation
If you use groupID %% artifactID % revision rather than groupID %
artifactID % revision (the difference is the double %% after the
groupID), sbt will add your project's Scala version to the artifact
name. This is just a shortcut. You could write this without the %%:
libraryDependencies += "org.scala-tools" % "scala-stm_2.9.1" % "0.3"
Assuming the scalaVersion for your build is 2.9.1, the following is
identical:
libraryDependencies += "org.scala-tools" %% "scala-stm" % "0.3"
The idea is that many dependencies are compiled for multiple Scala
versions, and you'd like to get the one that matches your project.
Your script seems to be getting Akka for scala 2.10 in "akka-actor_2.10" try renaming to your scala version.
Related
Does anyone have a bare-bones zio-grpc server, with codegen in the project also, working with Scala 3?
I started with the HelloWorld project from their repo and attempted to get it to build with scalaVersion := "3.1.0"
Here is the relevant section in plugins.sbt:
libraryDependencies ++= Seq(
"com.thesamet.scalapb.zio-grpc" % "zio-grpc-codegen_2.13" % zioGrpcVersion,
"com.thesamet.scalapb" % "compilerplugin_2.13" % "0.11.1"
)
excludeDependencies ++= Seq(
ExclusionRule("org.scala-lang.modules", "scala-collection-compat_2.12"),
ExclusionRule("com.thesamet.scalapb", "protoc-bridge_2.12")
)
and in build.sbt:
libraryDependencies ++= Seq(
"io.grpc" % "grpc-netty" % grpcVersion,
"com.thesamet.scalapb" % "scalapb-runtime-grpc_2.13" % scalapb.compiler.Version.scalapbVersion
)
excludeDependencies ++= Seq(
ExclusionRule("org.scala-lang.modules", "scala-collection-compat_2.12"),
ExclusionRule("com.thesamet.scalapb", "protoc-bridge_2.12")
)
Since Scala 3 can use 2.13 libraries, that's what I'm doing. (Of the three zio-grpc-related libs, one, zio-grpc-codegen, does not have a Scala 3 version, so 2.13 must be used at least for that one.)
I get this error from sbt with the versions as above:
java.lang.NoSuchMethodError: scala.package$.Seq()Lscala/collection/immutable/Seq$;
at protocbridge.gens$.java(gens.scala:17)
at protocbridge.gens$.(gens.scala:11)
If I remove either of the scala-collection-compat exclusions, we get
[error] Modules were resolved with conflicting cross-version suffixes in ProjectRef(uri("file:/Users/xxx/dev/zio-grpc/examples/helloworld/project/"), "helloworld-build"):
[error] com.thesamet.scalapb:protoc-bridge _2.12, _2.13
[error] com.thesamet.scalapb:compilerplugin _3, _2.13
In short, I cannot find any permutation of Scala 2.13/3 versions of zio-grpc-codegen, compilerplugin_3, and scalapb-runtime-grpc that will not give some sbt conflicting cross-version suffix error.
TL;DR: this is not possible yet as some of the code you are using rely on macros and is not yet published for Scala3.
SBT plugins runs with Scala 2.12 no matter which Scala version is used in your project, thus you don't have to try to use plugins with _2.13 or _3 suffix, just use the regular syntax that will actually pick _2.12 artifacts.
That is, in plugins.sbt:
libraryDependencies ++= Seq(
"com.thesamet.scalapb.zio-grpc" %% "zio-grpc-codegen" % zioGrpcVersion,
"com.thesamet.scalapb" %% "compilerplugin" % "0.11.8"
)
(No need for any exclusion).
You can confirm this by looking at sbt logs and you should see that it downloads plugins for version 2.12 of Scala:
...
https://somerepository.com/com/thesamet/scalapb/zio-grpc/zio-grpc-codegen_2.12/0.5.1/zio-grpc-codegen_2.12-0.5.1.pom
https://somerepository.com/com/thesamet/scalapb/compilerplugin_2.12/0.11.8/compilerplugin_2.12-0.11.8.pom
...
Once you do that, you'll get an error as following dependencies do not exist:
com.thesamet.scalapb:scalapb-runtime_3:0.11.1
com.thesamet.scalapb:scalapb-runtime-grpc_3:0.11.1
com.thesamet.scalapb.zio-grpc:zio-grpc-core_3:0.5.0
For the 1st and 2nd, you just have to update the compilerplugin version to 0.11.8 as I did already above (the compilerplugin version is used for the main dependency scalapb-runtime-grpc).
For the 3rd, unfortunately it's not published yet for Scala 3. One attempt is to force the _2.13 version for this one with something like that in the build.sbt:
libraryDependencies += ("com.thesamet.scalapb.zio-grpc" %% "zio-grpc-core" % "0.5.1") cross CrossVersion.for3Use2_13
excludeDependencies += "com.thesamet.scalapb.zio-grpc" % "zio-grpc-core_3"
But this doesn't compile with some errors related to macros, and that is something that is not compatible between Scala 2.13 and 3. You cannot workaround that.
Remember you can check available versions of a lib for a Scala version on Maven central:
https://mvnrepository.com/artifact/com.thesamet.scalapb/compilerplugin
https://mvnrepository.com/artifact/com.thesamet.scalapb.zio-grpc/zio-grpc-core
I haven't released zio-grpc for Scala 3 as some tests related to Has were failing and were tricky to fix. At the same ZIO 2 is coming out and deprecated Has. There's a version of zio-grpc with ZIO 2 and Scala 3 support coming soon.
I am trying to learn the basics of Scala, scalatest, and sbt and I'm following a tutorial. This is my built.sbt file:
name := "demo-hello"
version := "0.1"
scalaVersion := "2.12.6"
libraryDependencies += "org.scalatest" % "scalatest_2.10" % "2.1.0" % "test"
I have a test that looks like this (showing this is probably unnecessary:
package demo
import org.scalatest.FunSuite
class HelloTest extends FunSuite {
test("say hello method works correctly") {
val hello = new Hello
assert(hello.sayHello("Scala") == "Hello, Scala!")
}
}
What should I do from here? I am trying to run the test but I get this error:
Error:(8, 36) can't expand macros compiled by previous versions of Scala
assert(hello.sayHello("Scala") == "Hello, Scala!")
I'm not that familiar with the % symbol btw.
FIX
I changed my build.sbt to this:
name := "demo-hello"
version := "0.1"
scalaVersion := "2.10"
libraryDependencies += "org.scalatest" % "scalatest_2.10" % "2.1.0" % "test"
Remaining questions:
So it seems downgrading to scalaVersion "2.10" worked. Why?
What is an artifact? scalatest is apparently an artifact?
Where is scalaversion 2.10 kept on my machine? It seems I only have scala 2.12. Where in my project folder is version 2.10?
Answering your questions slightly out-of-order:
2 - An "artifact" is something that's built by maven, sbt, or another build system. For Scala or Java, this is almost always a jar file. Each item in libraryDependencies specifies a file in a maven repository (a database of artifacts).
1 - Scala class files are not compatible between minor versions of Scala. When you download a Scala jar from a maven repository, the Scala version is specified as part of the artifact name. The _2.10 in your dependency declares that you wish to use the version of scalatest that's compile for Scala 2.10 - which is why you were getting an error using it in your Scala 2.12 application.
When declaring dependencies on Scala artifacts in sbt, you should always use the %% operator, which automatically appends the appropriate suffix to your artifact, like so:
// This works for any scalaVersion setting.
libraryDependencies += "org.scalatest" %% "scalatest" % "2.1.0" % "test"
3 - sbt handles downloading the appropriate runtime files for the declared version of Scala automatically.
I have a spark streaming Scala project which uses Apache NiFi receiver. The projects runs fine under Eclipse/Scala IDE and now I want to package it for deployment now.
When I add it as
libraryDependencies += "org.apache.nifi" %% "nifi-spark-receiver" % "0.3.0"
sbt assumes it's a Scala library and tries to resolve it.
How doe I add NiFi receiver and all it's dependencies to project's SBT file?
Also, is it possible to pint dependencies to local directories instead of sbt trying to resolve?
Thanks in advance.
Here is my sbt file contents:
name := "NiFi Spark Test"
version := "1.0"
scalaVersion := "2.10.5"
libraryDependencies += "org.apache.spark" %% "spark-core" % "1.5.2" % "provided"
libraryDependencies += "org.apache.nifi" %% "nifi-spark-receiver" % "0.3.0"
libraryDependencies += "org.apache.nifi" %% "nifi-spark-receiver" % "0.3.0"
Double % are used for adding scala version as suffix to the maven artefact. It is required because different scala compiler versions produces incompatible bytecode. If you are would like to use java library from maven, then you should use single % character
libraryDependencies += "org.apache.nifi" % "nifi-spark-receiver" % "0.3.0"
I also found that I can put libraries the project depends on into the lib folder and they will be picked up during assembly.
I am new to scala and am currently trying to setup IntelliJ IDEA 13.1 with the Scala plugin. It has support for SBT. I have simply followed the basic tutorial for creating a new project for SBT here: http://confluence.jetbrains.com/display/IntelliJIDEA/Getting+Started+with+SBT
Currently my build.sbt file is:
name := "scalasandpit"
version := "1.0"
scalaVersion := "2.10"
libraryDependencies += "org.scalatest" % "scalatest_2.10" % "2.1.0" % "test"
autoAPIMappings := true
This pulls down various jar binaries, but no sources and no javadoc. I wondered if there is a way to have both sources and javadoc work with IntelliJ and SBT. I think I'm missing something.
There seem to be two issues: getting sbt to pull down sources and docs, and then getting Idea to show them to you. To solve the former problem see the sbt documentation -- about half way down there's a section called "Download Sources" which tells you what to add to your build.sbt:
libraryDependencies +=
"org.scalatest" % "scalatest_2.10" % "2.1.0" % "test" withSources() withJavadoc()
I'm trying to use scala-time with scala 2.10, and have found that it doesn't work with sbt correctly.
given something like
scalaVersion := "2.10.2"
libraryDependencies += "org.scalaj" %% "scalaj-time" % "0.7"
sbt will happily try to resolve http://repo1.maven.org/maven2/org/scalaj/scalaj-time_2.10/0.7/scalaj-time_2.10-0.7.pom.
Unfortunately, scalaj-time is publised with full scala versions as can be seen at http://central.maven.org/maven2/org/scalaj/.
It can be resolved with
libraryDependencies += "org.scalaj" % "scalaj-time_2.10.2" % "0.7"
but I'm wanting to know if this is a change in sbt behaviour, a bug in scala-time's build or if there's a way to configure sbt to pass the 3-part version instead of 2-part.
As Seth noted jorgeortiz85/scala-time likely was published using sbt that predates binary cross versioning convention that was introduced in sbt 0.12. You could do:
libraryDependencies += "org.scalaj" % "scalaj-time_2.10.2" % "0.7"
or
libraryDependencies += "org.scalaj" % "scalaj-time" % "0.7" cross CrossVersion.full
But then you'd be stuck with using 2.10.2 while Scala 2.10.4 is already out.
There's a similar Joda time wrapper named nscala-time/nscala-time that seems more actively maintained. Last updated 3 days ago and Scala 2.11.0 is supported already, so that could also be your option.
libraryDependencies += "com.github.nscala-time" %% "nscala-time" % "1.0.0"