Why I can't execute scala file?

Question

I am a newbie to Scala, it\'s the first time I\'m running Scala, when I installed Scala, I created a file named Hello.scala, the content is:

pr         


        

Answer 1

• Adding -nc flag saved my day.

  scala -nc Hello.scala

• What is -nc?

  -nc no compilation daemon: do not use the fsc offline compiler

  Source: http://alvinalexander.com/java/jwarehouse/scala-2.11/compiler/scala/tools/nsc/GenericRunnerCommand.scala.shtml

• What is fsc offline compiler?

  fsc – Fast offline compiler for the Scala 2 language

  Source: http://www.scala-lang.org/old/sites/default/files/linuxsoft_archives/docu/files/tools/fsc.html

Answer 2

If you’re on some flavor of Unix, you can run a Scala script as a shell script by prepending a pound bang directive at the top of the file.

For example, type the following into a file named helloarg:

#!/bin/sh
exec scala "$0" "$@"
!#
// Say hello to the first argument
println("Hello, "+ args(0) +"!")

The initial #!/bin/sh must be the very first line in the file.
Once you set its execute permission:

$ chmod +x helloarg

You can run the Scala script as a shell script by simply saying:

$ ./helloarg globe

If you’re on Windows, you can achieve the same effect by naming the file helloarg.bat and placing this at the top of your script:

::#!
@echo off
call scala % 0 % *
goto :eof
::!#

Answer 3

This works in mac for development.

#!/usr/bin/env scala -nc
println("hello");

Answer 4

Just a summary of what I know. I used to be confused by how to run a scala file properly.

In sum, we got 3 ways to achieve this:

1. For script files. For script, it means it's just as the same as you type lines of statements in the REPL, or use :paste mode to paste multiple lines. Something like:

   println("foo")

2. Compile an object containing main method with scalac. You can extends App trait to easily implement.

   def main(args: Array[String]) : Unit

You may say "You liar, there are just two ways". But for the second one, I think there's too ways to get it running.

1. scala -howtorun:object ObjectName -cp "./" : The -cp is just for insurance.
2. java -cp "/path/to/your/scala-jars" ObjectName : So the difference is just the classpath need to be included.

Answer 5

Write the println statement inside the main function:

object HelloWorld {   
 def main(args: Array[String]) {   
   println("Hello World!")   
 }   
}

Then execute: scala -nc HelloWorld.scala

Answer 6

When you are trying to run scala follow below steps:

1. Dont open scala REPL
2. use scala <filename.scala><Input if any> from cmd prompt

below is the example:

scala /home/prakash/Desktop/babyname.scala < /home/prakash/Desktop/ND

Note: above command must be typed in unix cmd prompt not in scala repl.