Oh please no! Static typing and Lisp - especially a Lisp like Arc that puts even more emphasis on being as dynamic as possible - don't mix. If we want performance improvements like this, that's what type annotations are for. Those work fine in CL for gaining performance, and integrate well into dynamic languages.
If we add Haskell's type system, we'll just end up with an ad hoc, informally-specified, bug-ridden, slow implementation of half of Haskell. That's not what anyone wants.
Err. The idea is that these are the "type annotations" you are looking for. I never said anything about making this mandatory; it's merely the implementation layer for type annotations.
