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Scala
1. Scala
Scala combines object-oriented and functional programming in one concise, high-level language. Scala's static types help avoid bugs in complex applications, and its JVM and JavaScript runtimes let you build high-performance systems with easy access to huge ecosystems of libraries. From the Scala web site at
https://www.scala-lang.org/ .
2. CentOS installation
Note: Scala is built on and requires Java. See
Java .
The following Linux command(s) to install Scala from the command line.
cd ~
wget http://downloads.lightbend.com/scala/2.11.8/scala-2.11-8.rpm
sudo yum -y install scala-2.11-8.rpm
cd ~
The following is intended to be run as a Bash script and not typed in at the command line.
The following Linux command(s) to install scala in a Bash script.
IVER1=scala-2.11-8
if [ -f /usr/bin/scala ]; then
echo -e "scala appears to be installed, nothing done"
else
cd ~
if [ -f ~/$IVER1.rpm ]; then
echo -e "$IVER1.rpm exists, nothing done"
else
echo -e "$IVER1.rpm not found, getting it"
wget http://downloads.lightbend.com/scala/2.11.8/$IVER1.rpm
fi
sudo yum -y install $IVER1.rpm
fi
3. Check the installed version
The following Linux command(s) to check the installed version of Scala.
scala -version
On
2019-08-15 the output was as follows.
Scala code runner version 2.11.8 -- Copyright 2002-2016, LAMP/EPFL
4. Hello world in Scala
The file type of a
Scala program file is
scala.
The following Linux command(s) create/edit a hello program in the your home directory using the nano text editor.
nano ~/hello.scala
Create the following program text in the editor that will output the text "Hello world"
object HelloWorld {
def main(args: Array[String]): Unit = {
println("Hello world")
}
}
To exit with save, remember to press
Ctrl-X, then "
y" (for yes) and
Enter to exit.
The following Linux command(s) run the program.
scala !/hello.scala
The output should be as follows.
Hello world
Note: Since Scala is Java-based and a somewhat sophisticated (read as complicated) system, you may need to wait a while for even a simple "Hello world" program to compile and run.
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