Quite often, especially if you make a variation of an existing class (or an extra type in an ADT). Scala does this quite transparent. Something defined as a `v

Quite often, especially if you make a variation of an existing class (or an extra type in an ADT). Scala does this quite transparent. Something defined as a `var` (variable), `val` (immutable variable), `lazy val` (lazy immutable variable) or `def` (method) is called source- and binary compatible from the caller side. I've never seen this trick anyone, except for maybe unexpected bad performance.