Re: eval, default-imports, and unexpected behavior

[Diego]

> running the following interpreted or compiled code works (but shouldn't)

After looking into this a little more, it seems the behavior of eval inside 
modules in compiled code is due to the last two lines of module.scm rather than 
`eval-handler`. I believe the stated explanations still hold true for 
interpreted code (and in either case, the behavior of eval inside modules 
remains dubious)

I experimented with commenting out these lines of `eval-hander`:

  ;; When se is empty, it's the first time eval was called:
  ;; ensure an active default environment.  We do it here because
  ;; eval does not work yet at the end of modules.scm, and we
  ;; don't want to inject calls into every toplevel (see #1437)
  (when (null? se)
      ((compile-to-closure
      `(##core#begin (import-for-syntax ,@default-syntax-imports)
                      (import ,@default-imports))
      '() #f #f #f #t) '()))

In which case it becomes much easier to implement a pure r5rs/r7rs switch, and 
nothing seemed to break on the surface (in trivial interpreted/compiled code 
tests), but to be honest I don't fully understand the comment that comes with 
it and did almost no testing, so I'm definitely missing something there.