###suspicious identifier: ? 


You can use ? as identifier:

    val l=List(1,2,3)
    val? =List(1,2,3)

Here it doesn't save you anything, because you can't stick it to the equal sign: 

    val ?=List(1,2,3) // illegal

But later on, it often saves one character, since you don't need a delimiter: 

    print(?size)  // l.size needs a dot
    def a(? :Int*)=(?,?tail).zipped.map(_-_)

However, it is often tricky to use: 

           print(?size)
    3
           print(?size-5)
    <console>:12: error: Int does not take parameters
           print(?size-5)
                  ^