Question

Just reading about Scala, and how the exists method that acts on collections reduces code duplication etc.

How could you write a function similar to exists that acts on collections yourself? Is it possible?

Sort of like a c# extension method that acts on a particular type.

Answer 1

Sure, you can do that using implicit conversions.

scala> implicit def foo[A](xs: Seq[A]) = new {
     |   def any(f: A => Boolean): Boolean = {
     |     for(x <- xs; if f(x)) return true
     |     false
     |   }
     | }
foo: [A](xs: Seq[A])java.lang.Object{def any(f: A => Boolean): Boolean}

scala> Seq(9, 11, 34).any(_ > 10)
res3: Boolean = true

scala> Seq(9, 11, 34).any(_ > 35)
res4: Boolean = false