scala-cli can use a specific java version using --jvm adopt:11 cli option like:
scala-cli compile . --jvm adopt:11
There's a java-home directive in scala-cli that can be specified in a scala file.
e.g
// Test.scala
//> using java-home "/Users/Me/jdks/11"
//> using scala "3.2.0"
Is there a jvm directive that can be used to specify the JVM version directly in the scala file instead of scala-cli command option?
e.g
// Test.scala
//> using jvm "adopt:11" -- is there a way to do this?
//> using scala "3.2.0"
scala-cli --jvm option
scala-cli java-home directive
This feature is now included in scala-cli v0.1.17.
https://github.com/VirtusLab/scala-cli/releases/tag/v0.1.17
//> using jvm "adopt:11"
Related
With scala 2 it was possible to pass system properties in the command line using -D<propname>=<propvalue> like in the following example:
$scala -Dpath.to.folder=/opt/myfolder
Scala v3 does not accept -D in the command line anymore:
$ scala -Dpath.to.folder=/opt/myfolder
bad option '-Dpath.to.folder=/opt/myfolder' was ignored
Welcome to Scala 3.1.0 (11.0.9.1, Java OpenJDK 64-Bit Server VM).
One possible solution (workaround) is to pass the properties through the environment:
$ env SYS_PROPS="-Dpath.to.folder=/opt/myfolder" scala
Welcome to Scala 3.1.0 (11.0.9.1, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.
scala> println(System.getenv().get("SYS_PROPS"))
-Dpath.to.folder=/opt/myfolder
scala>
How is it possible to pass system properties in the command line of scala 3 executables?
scala --help does not provide any useful info. Actually in scala 3.1.0 scala --help and scalac --help print the same message in the stdout.
I'm trying to get familiar with Scala. I am using macOS.
I've installed scala using brew install scala which is hassle-free and once complete I can launch the scala REPL simply by issuing scala and I'm at the scala> prompt.
I now want to import some packages, so I try:
import org.apache.spark.sql.Column
and unsurprisingly it fails with
error: object apache is not a member of package org
This makes sense, how would it know where to get that package from? Thing is, I don't know what I need to do to make that package available. Is there anything I can do from the command-line that would allow me to import org.apache.spark.sql.Column?
I have googled around a little but not found anything that explains in a jargon-free way. Complete Scala noob here so jargon-free responses would be appreciated.
Here are two ways to start a REPL with dependencies that I'm aware of:
Use SBT to manage dependencies, use console to start a REPL with those dependencies
Use Ammonite REPL
You could create a separate directory with a build.sbt where you set
scalaVersion := "2.11.12"
and then copy the
libraryDependencies += "org.apache.spark" %% "spark-sql" % "2.3.0"
snippets from MavenCentral. Then you can run the REPL with sbt console. Note that this will create a project and target subdirectories, so it "leaves traces", you can't use it like the standalone scala-repl. You could also omit the build.sbt, and add the library-dependencies by typing them into the SBT-shell itself.
Alternatively you can just use Ammonite REPL that has been created exactly for that purpose.
You can use classpath to make the lib available i.e. download the jar locally and use the command as follows (here I'm using Apache IO lib to move files from scala prompt )
C0:Desktop pvangala$ scala -cp /Users/pvangala/Downloads/commons-io-2.6/commons-io-2.6.jar
Welcome to Scala 2.12.5 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_161).
Type in expressions for evaluation. Or try :help.
scala> import java.io.File
import java.io.File
scala> val src = new File("/Users/pvangala/Downloads/commons-io-2.6-bin.tar")
src: java.io.File = /Users/pvangala/Downloads/commons-io-2.6-bin.tar
scala> val dst = new File("/Users/pvangala/Desktop")
dst: java.io.File = /Users/pvangala/Desktop
scala> org.apache.commons.io.FileUtils.moveFileToDirectory(src, dst, true)
If you want to use spark stuff I'd recommend you use the spark-shell that comes with the spark-installation. I don't know macOS so I can't help you much with the install of Spark there.
For normal Scala I recommend ammonite http://ammonite.io/#Ammonite-REPL that has included syntax to allow to pull packages/dependencies.
If you want to use spark, you should use the spark-shell instead the scala REPL. It has almost the same behaviour but includes all the spark dependencies by default.
You should download spark binaries from here
Then if you are using Linux, you should create the variable SPARK_HOME pointing to the downloaded folder and include its bin folder in PATH.
then you can start it in any console with the command spark-shell
In Windows i'm not sure, but i think that you should have a spark-shell.cmd file or something similar which you can use to start the spark-shell,
I did the following in Windows:
for /f "tokens=*" %%a in ('java -jar coursier fetch -p "com.lihaoyi::requests:0.2.0" "com.lihaoyi::upickle:0.7.5"') do set SCP=%%a
scala -nc -classpath %SCP% %1 %2 %3
Instead of the two libraries listed here you can use an unlimited number of other libraries you need. They must be available in maven central, though. The %1 could be a scala script (".sc" extension). But you could leave it empty and the REPL will start with the libraries on the classpath.
I've downloaded Algebird and I want to try out few things in the Scala interpreter using this library. How do I achieve this?
Of course, you can use scala -cp whatever and manually manage your dependencies. But that gets quite tedious, especially if you have multiple dependencies.
A more flexible approach is to use sbt to manage your dependencies. Search for the library you want to use on search.maven.org. Algebird for example is available by simply searching for algebird. Then create a build.sbt referring to that library, enter the directory and enter sbt console. It will download all your dependencies and start a scala console session with all dependencies automatically on the classpath.
Changing things like the scala version or the library version is just a simple change in the build.sbt. To play around you don't need any scala code in your directory. An empty directory with just the build.sbt will do just fine.
Here is a build.sbt for using algebird:
name := "Scala Playground"
version := "1.0"
scalaVersion := "2.10.2"
libraryDependencies += "com.twitter" % "algebird-core" % "0.2.0"
Edit: often when you want to play around with a library, the first thing you have to do is to import the namespace(s) of the library. This can also be automated in the build.sbt by adding the following line:
initialCommands in console += "import com.twitter.algebird._"
Running sbt console will not import libraries declared with a test scope. To use those libraries in the REPL, start the console with
sbt test:consoleQuick
You should be aware, however, that starting the console this way skips compiling your test sources.
Source: http://www.scala-sbt.org/0.13/docs/Howto-Scala.html
You can use the scala's -cp switch to keep jars on the classpath. There are other switches available too, for example, -deprecation and -unchecked for turning on various warnings. Many more to be found with scala -X... and scala -Y.... You can find out more information about these switches with scala -help
This is an answer using Ammonite (as opposed to the Scala REPL) - but it is such a great tool that it is worth mentioning.
You can install it with a one liner such as:
sudo sh -c '(echo "#!/usr/bin/env sh" && curl -L https://github.com/lihaoyi/Ammonite/releases/download/2.1.2/2.13-2.1.2) > /usr/local/bin/amm && chmod +x /usr/local/bin/amm' && amm
or using brew on macOS:
brew install ammonite-repl
For scala 2.10, you need to use an oder version 1.0.3:
sudo sh -c '(echo "#!/usr/bin/env sh" && curl -L https://github.com/lihaoyi/Ammonite/releases/download/1.0.3/2.10-1.0.3) > /usr/local/bin/amm && chmod +x /usr/local/bin/amm' && amm
Run Ammonite in your terminal:
amm
// Displays
Loading...
Welcome to the Ammonite Repl 2.1.0 (Scala 2.12.11 Java 1.8.0_242)
Use in ivy import to import your 3rd part library:
import $ivy.`com.twitter::algebird-core:0.2.0`
Then you can use your library within the Ammonite-REPL:
import com.twitter.algebird._
import com.twitter.algebird.Operators._
Map(1 -> Max(2)) + Map(1 -> Max(3)) + Map(2 -> Max(4))
...
Scala is installed and working fine.
scalacheck.jar is placed in the /bin .
I used the following command
$ scala -cp scalacheck.jar
After that, when i tried the below command,
scala> import org.scalacheck.Prop.forAll
I got the following error.
<console>:7: error: object scalacheck is not a member of package org
import org.scalacheck.Properties
^
I might have done some mistake in using scalacheck, please correct me and give the proper commands so that I can able to work with scalacheck in Ubuntu in interpreter mode.
Putting executable on the path isn't the same as jar being on the classpath, so your jar being in /bin didn't change anything.
Just use:
scala -cp path_to_your.jar
and you should be fine.
If for example, your scalachek.jar is in /bin then use:
scala -cp /bin/scalacheck.jar
edit:
Putting jars in /bin probably isn't the best idea.
You can use it like this:
kjozsa#walrus:~$ scala -version
Scala code runner version 2.9.2 -- Copyright 2002-2011, LAMP/EPFL
kjozsa#walrus:~$ locate scalacheck.jar
/usr/share/scala/lib/scalacheck.jar
kjozsa#walrus:~$ scala -cp /usr/share/scala/lib/scalacheck.jar
Welcome to Scala version 2.9.2 (OpenJDK 64-Bit Server VM, Java 1.7.0_03-icedtea).
Type in expressions to have them evaluated.
Type :help for more information.
scala> import org.scalacheck.Prop.forAll
import org.scalacheck.Prop.forAll
scala>
Is it possible to include a jar file run running the Scala interpreter?
My code is working when I compile from scalac:
scalac script.scala -classpath *.jar
But I would like to be able to include a jar file when running the interpreter.
In scala2.8,you can use
scala>:jar JarName.jar
to add a jar to the classpath.
In Scala 2.8.1, it is not :jar but :cp
And in Scala 2.11.7 it is not :cp but :re(quire)
According to scala executable help all options of scalac are allowed ,
so you can run scala -classpath some.jar, i've just tried and it looks like it works
Include multiple jars int Scala REPL 2.10.0-RC2
scala -classpath my_1st.jar:my_2nd.jar:my_3rd.jar
in my case i am using Scala code runner version 2.9.2. and i had to add quotation marks.
I am using this jar files:
jdom-b10.jar, rome-0.9.jar
and everything goes fine with this:
scala -classpath "*.jar" feedparser.scala
In Scala version 2.11.6 from scala REPL use :require, can best be figured out by using :help from REPL
For example:
$ scala
Welcome to Scala version 2.11.6 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_45).
Type in expressions to have them evaluated.
Type :help for more information.
scala> :require lift-json_2.11-3.0-M5-1.jar
Added '<path to lift json library>/lift-json/lift-json_2.11-3.0-M5-1.jar' to classpath.
Scala version 2.11.5:
Here is an example of adding all jars in your ivy cache:
scala -cp /Users/dbysani/.ivy2/cache/org.apache.spark/spark-streaming_2.10/jars/*
scala> import org.apache.spark.streaming.StreamingContext
import org.apache.spark.streaming.StreamingContext
You can also create a local folder of all the jars that you need to get added and add it in a similar way.
Hope this helps.
"lib/*.jar" generates a list with blank between items not ":" or ";" as required.
Since Java 6 "lib/*" should work, but sometimes doesn't (classpath is set somewhere else)
I use a script like:
Windows:
#rem all *.jars in lib subdirectory
#echo off
set clp=.
for %%c in (lib\*.jar) do call :Setclasspath %%c
echo The classpath is %clp%
scala -classpath %clp% script.scala
exit /B %ERRORLEVEL%
:Setclasspath
set clp=%clp%;%~1
exit /B 0
Linux:
#!/bin/bash
#all *.jars in lib subdirectory
clp="."
for file in lib/*
do
clp="$clp:$file"
done
echo $clp
scala -classpath $clp script.scala