[Grace-core] Equality

[Kim Bruce]

We've been discussing how to define equality on and off for a while.  If you want your head to hurt, read Chapter 28 (Object Equality) in "Programming in Scala" by Odersky, Spoon, and Venners.  It's worth reading as it helps you avoid many of the wrong ways of defining it.  It is enough to make you want a ThisType (though even then you have to think it through carefully)!

Kim