$ copy-file changes/MacroCompileError.scala Macro.scala
> clean
> compile

$ copy-file changes/MacroRuntimeError.scala Macro.scala
> clean
> compile

$ copy-file changes/Main.scala Main.scala
$ copy-file changes/Macro.scala Macro.scala
> clean
> run

# use an implemntation of the macro that emits a compile-time error
$ copy-file changes/MacroCompileError.scala Macro.scala
-> compile

$ copy-file changes/Macro.scala Macro.scala
> clean
> compile

$ copy-file changes/MacroRuntimeError.scala Macro.scala
-> run
