CODEWITHSUNDEEP
scala-2.8
user693384
user693384

Reputation: 11

Scala dynamic typing, type bounds and java objects - is this expected behavior or a bug?

Sorry if this has been covered already. The following simple example of dynamic typing and type bounds does not work with a list of strings but works perfectly well with a (scala) class containing a defined length() function. Is this expected behavior or a bug? If it is expected behavior, is there a way to define the type bound such that it would work for a List of String objects as well as a list of arbitrary scala objects with a length(0 function?

def sumlen[T <: {def length : Int}](l : List[T]) : Int = {
     def sl(l : List[T], acc : Int) : Int = l match {
         case Nil => acc
         case h::t => sl(t, h.length + acc)
     }
     sl(l, 0)
}

val l1 = List("This", "is", "a", "test")

sumlen(l1)

Upvotes: 1

Views: 160

Answers (1)

shellholic
shellholic

Reputation: 6114

This works:

def sumlen[T <: {def length() : Int}](l : List[T]) : Int = {
//                         ^^

And yes, it is a feature, not a bug.

Upvotes: 2

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