Scala: Pattern matching when one of two items meets some condition

Question

I\'m often writing code that compares two objects and produces a value based on whether they are the same, or different, based on how they are different.

So I might writ

Answer 1

If you have to support arbitrary predicates you can derive from this (which is based on Daniel's idea):

List(v1, v2) filter (_ %2 == 0) match {
    case List(value1, value2) => "a"
    case List(value) => "b"
    case _ => "c"
}

the definition of the function:

def filteredMatch[T,R](values : T*)(f : T => Boolean)(p: PartialFunction[List[T], R]) : R = 
    p(List((values filter f) :_* ))

Now you can use it like this:

filteredMatch(v1,v2)(_ %2 == 0){
    case List(value1, value2) => "a"
    case List(value) => "b"
    case _ => "c"
}

I'm not so sure if it's a good idea (i.e. readable). But a neat exercise nonetheless.

It would be nice if you could match on tuples: case (value1, value2) => ... instead of lists.