ometa WaebricParser <: Parser {
  module = myList(#letter, ".") ,
  letter = "a",
  myList :n :s = apply(n) (apply(s) apply(n))*
}

program = 'a.'
try{
tree = WaebricParser.matchAll(program, "module")
}catch(exception){
 
   alert(exception.name)
 
}