Is the Sussman...

...coming up with a new programming language?
http://groups.csail.mit.edu/mac/users/gjs/propagators/
http://www.infoq.com/presentations/We-Really-Dont-Know-How-To-Compute
"I'm at the Strange Loop conference and Gerald Sussman said that all languages are obsolete but called Haskell "the most advanced obsolete language he knows". That's kind of a compliment I guess." - deech

>>45
You are missing the point. I'm talking about what sbcl does, not what the common lisp standard demands. It's detecting these type errors by collecting constraints based upon how you use arguments to functions (in fact sbcl will trace type constraints as you step into if statements). You can build these constraints for all functions in a module and generate a signature for each one. Then check that the generated constraints are satisfied when a function from another module is called. For generating efficient code, you have the choice of using a single function that handles generic types, or multiple compilations of the same function that handle different type cases. These would be compiled upon demand when called from other modules. In order for this to scale, an intermediate representation of the function in it's generic form would be made available to the other modules. C++ solves this problem badly with templates.