On Thu, Apr 17, 2008 at 03:41:06PM -0500, John M. Dlugosz wrote: > The multi-dictionary search didn't show this usage of covariance and > contravariance. But the series of articles on Type Theory in JOT uses > it to mean "in the same direction" and "in the opposite direction" but > doesn't define it as absolute subtyping directions. How is it being > used in this mailing list?
See <http://en.wikipedia.org/wiki/Covariance_and_contravariance_%28computer_science%29> for the generic CS definition. An interesting source might also be Scala's design on this issue: <http://www.scala-lang.org/intro/variances.html>. -- Ilmari Vacklin