To add to my previous answer on Abstract type vs. parameters, you have also the JESSE EICHAR’s recent blog post (2010, May 3rd) highlighting some key differences: trait C1[A] { def get : A def doit(a:A):A } trait C2 { type A def get : A def doit(a:A):A } In C2 case, the parameter is … Read more
This is what this.type is for: scala> abstract class Abstract0 { | def setOption(j: Int): this.type | } defined class Abstract0 scala> class Concrete0 extends Abstract0 { | var i: Int = 0 | def setOption(j: Int) = {i = j; this} | } defined class Concrete0 scala> (new Concrete0).setOption(1).setOption(1) res72: Concrete0 = Concrete0@a50ea1 As … Read more
You have a good point of view on this issue here: The Purpose of Scala’s Type System A Conversation with Martin Odersky, Part III by Bill Venners and Frank Sommers (May 18, 2009) Update (October2009): what follows below has actually been illustrated in this new article by Bill Venners: Abstract Type Members versus Generic Type … Read more