Currently the semantics of calling set! or define on an imported binding is undefined. Do we want to specifically make this an error?
R6RS, Chez's Modules, and Racket's module forms all, to my knowledge enforce immutability constraints on imported identifiers. I am inclined to think that this is something we want to maintain. I think immutable imports makes more sense both from efficiency and code reasoning perspectives. Otherwise, I think we could have a lot of confusion concerning bindings and evaluation orders when invoking libraries.
We voted this is an error.
I think we want importing bindings to be immutable in a module and mutable at the REPL.