[R6RS] Modules, a second question

[Manuel Serrano]

> (module foo r6rs
>   (display (foo 3))
>   (define (foo x) x))
> 
> Because the first definition of this module must signal an error,
> Manuel writes:
> 
> > If it does I don't see how the compiler will be able to do a good job
> > when compiling function calls...
> 
> First, let me say that I don't think it's terribly important for
> a compiler to optimize top-level expressions, which are the only
> ones that are made more difficult to optimize by the left-to-right
> order of evaluation here.
This problem does not concern the top level forms.
Consider:

-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----
(module foo r6rs
  (provides gee)

  (if (read)
      (foo))

  (define (foo)
     (let loop ((n 1000000000000000000000000000000000000000000000))
        (if (> n 0)
            (begin
               (bar n)
               (loop (- n 1))))))

  (define (bar n)
      <whatever you want>)

  (define (gee)
      ...(foo)...))
-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----|-----

Except if the compiler is particularly clever, the call to "bar" in "foo"
will be poorly compiled. Thus, the "external" call to "gee" will be
inefficient...

-- 
Manuel