It is possible to build all kinds of crazy type stuff into any lisp. Look at Qi or Typed Racket they build all kinds of type-stuff into the language (Im not an expert in stuff like this so I don't know how far you could go). There are allready people working on this in Clojure.
A Typesystem in this still combind with some tools to check this befor you run the programm should provide almost everything you get from Haskell or Scala.
This kind of approach does yield the additional benefits:
1. Much easier to change
2. You can add another static analysing system ontop of it
Comments
It is possible to build all kinds of crazy type stuff into any lisp. Look at Qi or Typed Racket they build all kinds of type-stuff into the language (Im not an expert in stuff like this so I don't know how far you could go). There are allready people working on this in Clojure.
A Typesystem in this still combind with some tools to check this befor you run the programm should provide almost everything you get from Haskell or Scala.
This kind of approach does yield the additional benefits:
1. Much easier to change
2. You can add another static analysing system ontop of it
3. Less restrictive