scaladyno-plugin

scaladyno is an attempt to make scala a more dynamic language :)

Scaladyno doesn't have a maintainer atm, since @CedricBastin is busy with other projects. Without proper support and engineering, we can't recommend anyone to use scaladyno on large code bases. Really sorry about that! If you're interested in becoming a maintainer, drop @CedricBastin or @VladUreche an email.

Let's take the following example:

$ cat demo.scala 

package dyno.demo

object Test {
  def main(args: Array[String]): Unit = {
    print("line> ")
    if (io.StdIn.readLine() != "boo") {
      println("okay")
    } else {
      val x = new NoSuchClass
      x.foo()
    }
  }
}

And try to compile it:

$ scalac demo.scala 
demo.scala:10: error: not found: type NoSuchClass
      val x = new NoSuchClass
                  ^
one error found

Of course, it doesn't compile.

But what if we use ScalaDyno? It should :)

First, let's set it up:

$ git clone https://github.com/scaladyno/scaladyno-plugin.git
$ cd scaladyno-plugin
$ sbt package

You should also have a local instalaltion of Scala 2.11.2 and the SCALA_PATH set to its bin directory. Now you can run:

$ ./dy-scalac demo.scala 
demo.scala:10: warning: [suppressed error] not found: type NoSuchClass
      val x = new NoSuchClass
                  ^
one warning found

Wow, it compiles. Now let's try to run it:

$ scala dyno.demo.Test
line> ok
okay

$ scala dyno.demo.Test
line> boo
java.lang.RuntimeException: Deferred compile-time error(s):

demo.scala:10: not found: type NoSuchClass
      val x = new NoSuchClass
                  ^
Stacktrace:
	at scala.sys.package$.error(package.scala:27)
	at dyno.demo.Test$.main(demo.scala:7)
	at dyno.demo.Test.main(demo.scala)
	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
	at java.lang.reflect.Method.invoke(Method.java:606)
	at scala.reflect.internal.util.ScalaClassLoader$$anonfun$run$1.apply(ScalaClassLoader.scala:68)
	at scala.reflect.internal.util.ScalaClassLoader$class.asContext(ScalaClassLoader.scala:31)
	at scala.reflect.internal.util.ScalaClassLoader$URLClassLoader.asContext(ScalaClassLoader.scala:99)
	at scala.reflect.internal.util.ScalaClassLoader$class.run(ScalaClassLoader.scala:68)
	at scala.reflect.internal.util.ScalaClassLoader$URLClassLoader.run(ScalaClassLoader.scala:99)
	at scala.tools.nsc.CommonRunner$class.run(ObjectRunner.scala:22)
	at scala.tools.nsc.ObjectRunner$.run(ObjectRunner.scala:39)
	at scala.tools.nsc.CommonRunner$class.runAndCatch(ObjectRunner.scala:29)
	at scala.tools.nsc.ObjectRunner$.runAndCatch(ObjectRunner.scala:39)
	at scala.tools.nsc.MainGenericRunner.runTarget$1(MainGenericRunner.scala:72)
	at scala.tools.nsc.MainGenericRunner.process(MainGenericRunner.scala:94)
	at scala.tools.nsc.MainGenericRunner$.main(MainGenericRunner.scala:103)
	at scala.tools.nsc.MainGenericRunner.main(MainGenericRunner.scala)

So, where's the magic? It's in ScalaDyno:

$ ../dy-scalac -Xprint:typer,dyno demo.scala 
demo.scala:10: warning: [suppressed error] not found: type NoSuchClass
      val x = new NoSuchClass
                  ^
[[syntax trees at end of                     typer]] // demo.scala
package dyno.demo {
  object Test extends scala.AnyRef {
    def <init>(): dyno.demo.Test.type = {
      Test.super.<init>();
      ()
    };
    def main(args: Array[String]): Unit = {
      scala.this.Predef.print("line> ");
      if (scala.io.StdIn.readLine().!=("boo"))
        scala.this.Predef.println("okay")
      else
        {
          val <x: error>: <error> = new <NoSuchClass: error>();
          <x: error>.<foo: error>()
        }
    }
  }
}

[[syntax trees at end of              dyno-prepare]] // demo.scala
package dyno.demo {
  object Test extends scala.AnyRef {
    def <init>(): dyno.demo.Test.type = {
      Test.super.<init>();
      ()
    };
    def main(args: Array[String]): Unit = {
      scala.this.Predef.print("line> ");
      if (scala.io.StdIn.readLine().!=("boo"))
        scala.this.Predef.println("okay")
      else
        `package`.this.error("Deferred compile-time error(s):\n\ndemo.scala:10: not found: type NoSuchClass\n      val x = new NoSuchClass\n                  ^\nStacktrace:")
    }
  }
}

one warning found

If you want to learn more about scaladyno and how it works, see this SCALA'14 paper