I recently gave up trying to use Scala in Eclipse (basic stuff like completion doesn't work). So now I'm trying IntelliJ. I'm not getting very far.

This was the original error. See below for update:

Scala signature Predef has wrong version
Expected 5.0
found: 4.1 in .... scala-library.jar

I tried both versions 2.7.6 and 2.8 RC1 of scala-*.jar, the result was the same.

JDK is 1.6.u20.

UPDATE

Today I uninstalled IntelliJ 9.0.1, and installed 9.0.2 Early Availability, with the 4/14 stable version of the Scala plug-in.

Then I setup a project from scratch through the wizards:

• new project from scratch
• JDK is 1.6.u20
• accept the default (project) instead of global / module
• accept the download of Scala 2.8.0beta1 into project's lib folder

Created a new class:

object hello {
  def main(args: Array[String]) {
    println("hello: " + args);
  }
}

For my efforts, I now have a brand-new error :)

Here it is:

Scalac internal error: class java.lang.ClassNotFoundException [java.net.URLClassLoader$1.run(URLClassLoader.java:202), java.security.AccessController.doPrivileged(Native Method), java.net.URLClassLoader.findClass(URLClassLoader.java:190), java.lang.ClassLoader.loadClass(ClassLoader.java:307), sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301), java.lang.ClassLoader.loadClass(ClassLoader.java:248), java.lang.Class.forName0(Native Method), java.lang.Class.forName(Class.java:169), org.jetbrains.plugins.scala.compiler.rt.ScalacRunner.main(ScalacRunner.java:72)]

Thanks