Scala: constant in pattern matching or always do a Unit testing!

Every Scala coder should remember the difference between Constant and Variable patterns in
pattern matching. Short refresh from this topic: if pattern starts from low case letter: it is counted as a variable. We can still use a lowercase name for a pattern constant, using one of two tricks:
1). If the constant is a field of any object, we can prefix it with a qualifier. For example, name is a variable pattern, but this.name or objInstance.name. 

2) Second workaround is enclosing the variable name with back ticks. For instance, `name` would again be interpreted as a constant, not as a variable.

Here an example for constant, constructor, sequence and default matching cases, using the List:

	val myList = List(1, 2)
	val res = myList match {
	case `myList` => "instance itself"
	case List(_) => "one element"
	case List(_, _) => "two elements"
	case _ => "unknown"
	}
	println(res) // instance itself

view raw ok.scala hosted with ❤ by GitHub

And funny situation when it doesn't work (looks like it is fixed in betas of 2.10):

	val myList = List(1, 2)
	val res = myList match {
	case List(_) => "one element"
	case `myList` => "instance itself"
	case List(_, _) => "two elements"
	case _ => "unknown"
	}
	println(res) // two elements

view raw error.scala hosted with ❤ by GitHub

Just few line of code with simple behaviour (depends on standart library and language construction only). Of course don't trust Scala isn't the outcome, just always do a Unit testing.