Yes, SBCL, where declarations are treated as assertions (before you reach it, you must prove it or test it, after the declaration you can assume it). No, (∀a.

Yes, SBCL, where declarations are treated as assertions (before you reach it, you must prove it or test it, after the declaration you can assume it). No, (∀a. a → a) is not easily expressible (unless you write your own DSL).