Addressing someone like a tardy child (I'm not mad, just disappointed) is a reliable way to inflame the discussion. I don't think I will respond if you phrase a

Addressing someone like a tardy child (I'm not mad, just disappointed) is a reliable way to inflame the discussion. I don't think I will respond if you phrase any further replies like that. The claim that "dynamic typing is incompatible with performance" is considerably stronger than what I said (and I would contend belies an imprecise if not misguided notion of "dynamic typing"). That being said, for people interested in using a mainstream platform to develop their applications, the JVM offers a number of extremely productive "dynamic" languages none of which perform as well as Java across a broad spectrum of activities. I think you will find it telling that the engineers at Facebook (who are world-class) chose to implement this system in Java. Optional type annotations are a wonderful idea and I am optimistic that someday the tradeoffs we mark around performance and convenience can be granular and addressable at a lexical level in a single file. Until then, the mix of a JVM scripting language and code written in native Java calling each other trivially is pretty damn close. Now I invite you to write a similar system using SBCL, if you enjoy debugging inexplicable concurrency failures. Or maybe you'll use Actionscript 3? I hear it has optional type annotations. Now if you'll excuse me, I need to go work for the Man on dreary accounting software. Fail.