scala

mcnalu · 10-30-2011, 05:03 AM

I've installed scala on slackware 13.37 32bit using a script from slackbuilds.org

In the interpreter it works fine, but it just hangs and gives no output when I try and run any code from the command line with something like

Code:

$ scala hello.scala

where the file hello.scala is something like

Code:

println("Hello, world, from a script!")

or even a more java-like explicit class:

Code:

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

Any one else got past this?

pgeek · 10-30-2011, 07:44 AM

I don't know scala, but where do you call that "function"?
Don't you need something like this:

Code:

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

?

mcnalu · 10-30-2011, 09:09 AM

Apparently you don't have to with a code fragment like the first example.

With the second I tried explicitly calling main too but same result.

kfritz · 10-30-2011, 11:47 AM

Tried it on x86_64 (13.37) and 32-bit (current), and your first example works for me.

Try running with strace and see if you can figure out where it's getting stuck.

pgeek · 10-30-2011, 02:22 PM

Ok, tried it and it works.
Here they tell you, that you have to compile it first with scalac.

Code:

$ cat HelloWorld.scala
object HelloWorld {
  def main(args: Array[String]) {
    println("Hello, world! ")
  }
}
$ scalac HelloWorld.scala
$ scala HelloWorld
Hello, world!

mcnalu · 10-30-2011, 06:30 PM

I've seen that page and it's the example of "Script it!" above the one you quote that doesn't work for me.

It should be possible to run scala programs without a scalac compile first, e.g. here.

Cedrik · 10-30-2011, 06:40 PM

Maybe the output is buffered, so it needs a new line to flush

println("Hello, world, from a script!\n")

Just a thought, I don't know really
[edit]
I doubt it, as println seems to produces newlines automatically...

pgeek · 10-31-2011, 07:08 AM

Quote:

Originally Posted by mcnalu

I've seen that page and it's the example of "Script it!" above the one you quote that doesn't work for me.

It should be possible to run scala programs without a scalac compile first, e.g. here.

I just installed the SBo package on Slackware 13.37 32bit and all examples worked for me.

I tried again:

Code:

$ which scala
/usr/lib/scala/bin/scala
$ cat HelloWorld.scala 
println("Hello world!")
$ scala HelloWorld.scala 
Hello world!
$ cat HelloWorld2.scala 
object HelloWorld {
  def main(args: Array[String]) {
    println("Hello, world!")
  }
}
HelloWorld.main(args)
$ scala HelloWorld2.scala
Hello, world!

And now the last output didn't appear until I clicked into xterm... strange.

Edit:
When I tried running the second example without "HelloWorld.main(args)" and without compiling, I received an error message. It seems, that you have to add this line only when running without compiling it first.

Sorry, I know C, C++, Ruby, Python and very little Java... never worked with scala

pino_otto · 10-31-2011, 07:19 AM

From a book about Scala:

By the way, 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

pino_otto · 10-31-2011, 07:22 AM

I installed scala by downloading it from the scala website.

It works also with scripts, without compiling them in advance.

That is a nice feature of scala.

mcnalu · 10-31-2011, 09:24 AM

pgeek

Thanks for trying it out - very helpful, here's what I get when I do the same:

Quote:

$ which scala
/usr/lib/scala/bin/scala
$ cat HelloWorld.scala
println("Hello world!")
$ scala HelloWorld.scala
^C
$

The ^C is me having to interrupt it - clicking doesn't cause the output to appear, in any terminal.

I'll try reinstalling and looking more closely at the slackbuild.

pino_otto - yes, it's handy to run scala like an interpreted language - hence my desire to get it working! I tried the bash script approach but it also gives no output

pino_otto · 11-01-2011, 06:48 AM

did you set the variable SCALA_HOME

if you give the command:

$ echo $SCALA_HOME

what do you see?

mcnalu · 11-02-2011, 07:28 AM

Yup - seems fine.

Code:

$ echo $SCALA_HOME
/usr/lib/scala
$ ls /usr/lib/scala
bin/  lib/  man/  meta/  misc/  src/