Run groovy script from within gradle

What's the best way to create a gradle task, which runs a groovy script? I realize that gradle build files are groovy, so I would think it would be possible to do something like this:

task run << {
    Script app = new GroovyShell().parse(new File("examples/foo.groovy"))
    // or replace .parse() w/ a .evalulate()?
    app.run()
}

I get all kinds of whacky errors when I try this if bar.groovy is using @Grab annotations or even doing simple imports. I want to create a gradle task to handle this, so that I can hopefully reuse the classpath definition.

Would it be better to move the examples directory into the src directory somewhere? What's a best practice?