In the last version of scala (2.10.3) REPL, I can type exit to quit from REPL. However, in Scala 2.11.0 this doesn't work.
$ scala
Welcome to Scala version 2.11.0 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_51).
Type in expressions to have them evaluated.
Type :help for more information.
scala> exit
<console>:8: error: not found: value exit
exit
^
scala>
I ran into the same issue on upgrade, just use colon q.
:q
Additionally, exit was deprecated in 2.10.x with sys.exit suggested instead, so this works as well:
sys.exit
As a side note, I think they did this so you can distinguish between exiting the scala console in sbt and exiting sbt itself, though I could be wrong.
You options to leave the REPL as stated in the answers before are:
:quit
:q
Ctrl + d // Unix
Ctrl + z // Windows
sys.exit
Use the end of file characters. Ctrl-D on linux, Ctrl-Z on Windows.
Using the :help command on my 2.10.3 REPL gets me this hint:
:quit exit the interpreter
I don't know whether :quit is still there in 2.11.0 or not though.
When I use exit in 2.10.4, I got a warning:
warning: there were 1 deprecation warning(s); re-run with -deprecation for details
You can use:
:q
:quit
sys.exit
all of them work in 2.11.x.
You can use
sys.exit
OR
:q
to exit the shell
For sbt 1.4.1 commands use below command
exit:Terminates the remote client or the build when called from the console.
shutdown:Terminates the build.
Example
vudikeri#C02CP3LAMD6M scala % sbt version
[info] welcome to sbt 1.4.1 (N/A Java 14.0.1)
sbt:scala> shutdown
[info] shutting down sbt server
vudikeri#C02CP3LAMD6M scala %
sbt:scala> exit
[info] shutting down sbt server
Related
First I delete the .sbt from my home-directory, then I make an empty project directory, and in that directory I create a build.sbt file:
echo 'ThisBuild / scalaVersion := "3.1.3"' > build.sbt
Then I run sbt console and at the console prompt attempt the following Class.forname() invocation, which produces the following ClassNotFoundException:
[info] welcome to sbt 1.7.1 (Debian Java 11.0.16)
Welcome to Scala 3.1.3 (11.0.16, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.
scala> Class.forName("java.sql.Connection")
java.lang.ClassNotFoundException: java.sql.Connection
at dotty.tools.repl.AbstractFileClassLoader.findClass$$anonfun$1(AbstractFileClassLoader.scala:46
On the other hand, if I start the REPL with the plain-old scala command, then invoke the same forName() I see this:
Welcome to Scala 3.1.3 (11.0.16, Java OpenJDK 64-Bit Server VM).
Type in expressions for evaluation. Or try :help.
scala> Class.forName("java.sql.Connection")
val res0: Class[?] = interface java.sql.Connection
So the same forName() invocation elicits different behavior in the sbt console versus the Scala REPL: a ClassNotFoundException in the former versus returning an instance of the Class class in the latter.
The sbt console also produces that ClassNotFoundException with any of the following lines in the build.sbt file:
classLoaderLayeringStrategy := ClassLoaderLayeringStrategy.AllLibraryJars
or
classLoaderLayeringStrategy := ClassLoaderLayeringStrategy.ScalaLibrary
or even
classLoaderLayeringStrategy := ClassLoaderLayeringStrategy.Flat
What is it about sbt that causes the exception, and how can sbt be made to succeed?
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.
These simple lines in build.gradle expose a repl task that would ideally fire up a scala REPL. Fire up and keep alive that is. After the repl loads, it immediately receives a :quit command and exits.
Important parts of build.gradle:
dependencies{
compile "org.scala-lang:scala-library:2.11.7"
compile "org.scala-lang:scala-compiler:2.11.7"
}
task repl(type:JavaExec) {
main = "scala.tools.nsc.MainGenericRunner"
classpath = sourceSets.main.runtimeClasspath
}
Launching the REPL:
% gradle repl
:compileJava UP-TO-DATE
:compileScala UP-TO-DATE
:processResources UP-TO-DATE
:classes UP-TO-DATE
:repl
Welcome to Scala version 2.11.7 (OpenJDK Server VM, Java 1.7.0_91).
Type in expressions to have them evaluated.
Type :help for more information.
scala> :quit
BUILD SUCCESSFUL
Total time: 31.177 secs
REPL quits automatically immediately after launching. How to not have the REPL quit immediately?
You also need to redirect console input to your javaexec java process. Try adding standardInput System.in to your task definition. In my case, I also found it necessary to add args '-userjavacp'.
task repl(type:JavaExec) {
main = "scala.tools.nsc.MainGenericRunner"
classpath = sourceSets.main.runtimeClasspath
standardInput System.in
args '-usejavacp'
}
and finally running gradle with the -q option suppresses the gradle progress prompts giving me a cleaner scala repl.
I run Windows 7.
I have java (a current enough version to run scala) and scala downloaded on my computer. I've set PATH so that when I type "scala" into the command prompt it sends me to the proper interface:
Welcome to Scala version 2.9.1.final (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_51)
Type in expressions to have them evaluated.
Type :help for more information
However I can't execute the command "scala" or "scalac" on my test files.
scala> scala Hello
(console):8: error: object Hello is not a member of package scala
This makes me think I'm in the wrong directory. The file Hello.scala is saved in the home directory that I set PATH to.
However I get a different issue when I try to compile code.
scala> scalac Hello.scala
(console):1: error: ';' expected but '.' found.
I actually got my test file to work at one point... but I wasn't actually IN scala.
C:\scala-2.9.1.final\bin> scala Hello.scala
Hello world!
I'm not really sure how to proceed from here. If anyone has any ideas of what may be wrong I would greatly appreciate input.
It appears that you're trying to run & compile programs from within the Scala REPL (read-evaluate-print loop - a kind of Scala interpreter) and you cannot do that in the REPL. The REPL allows you to type in Scala statements and see them execute immediately. (If you're not sure how you entered the REPL, you probably just entered the command scala from the command line.) The REPL is useful for testing ideas, and for experimenting with Scala. For example:
C:\some\path> scala
Welcome to Scala version 2.11.8 (Java HotSpot(TM) 64-Bit Server VM, Java 1.8.0_91).
Type in expressions for evaluation. Or try :help.
scala> println ("Hello!")
Hello!
scala> val x = 10
x: Int = 10
scala> val y = x * 5
y: Int = 50
scala> sys.exit
C:\some\path>
However, the REPL isn't what you would use to compile & run Scala programs - you need to do that from the command line (or from a tool such as sbt). If you want to run your program directly from the command line, without using the REPL (that is, without being in Scala, as you put it) then you would need to do the following:
Firstly, compile your program using scalac:
C:\some\path> scalac Hello.scala
If that succeeds, you can then run the program with the scala command (which looks for a Hello.class file):
C:\some\path> scala Hello
(Here C:\some\path is the location of the files Hello.scala & Hello.class.)
Alternatively, as you have already discovered, you can run your Scala program as a script in the REPL. You can do this from the command line as follows (note the addition of the filetype .scala after Hello compared to the command above):
C:\some\path> scala Hello.scala
or from within the REPL:
scala> :load Hello.scala
Hope this helps!
You don't have to issue scala command when you're inside REPL. If you want to execute code from that file, load it:
here is what I have in Foo.scala
println("I'm foo")
Now I'm starting the REPL (and as you can see scala> is a sign that you're ALREADY into REPL and can start execute raw scala code):
Welcome to Scala version 2.10.3 (Java HotSpot(TM) 64-Bit Server VM, Java 1.7.0_25).
Type in expressions to have them evaluated.
Type :help for more information.
scala> :load Foo.scala
Loading Foo.scala...
I'm foo
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>