- We can now redefine imported identifiers.
- We can now use let-syntax, letrec-syntax, and modules at
top-level.
Hand-wavey Repl Semantics:
- Imported identifiers mean what they meant previously. In
particular, you cannot set! imported identifiers.
- An imported identifier may be redefined using define. Once
something is defined at the top-level, a specific location for it
is created, and all definitions, references, and set!s to that
variable go through the top-level location.
- Re-importing an identifier shadows the top-level location.
- Redefining re-exposes the top-level location.
- and do on.
- A reference to an unbound variable also fabricates a top-level
location for that variable.
Let's see how this goes.
