here you go. Variance explained by Martin Odersky in his coursera course https://class.coursera.org/progfun-005/lecture/83 https://class.coursera.org/progfun-0

here you go. Variance explained by Martin Odersky in his coursera course https://class.coursera.org/progfun-005/lecture/83 https://class.coursera.org/progfun-005/lecture/83 (you need to login to watch it). Or the Scala doc http://docs.scala-lang.org/tutorials/tour/variances.html http://docs.scala-lang.org/tutorials/tour/variances.html