> Provided that the following function is defined
>         (define (read-all-as-a-begin-expr filename)
>           (with-input-from-file filename
>              (lambda ()
>                (cons 'begin
>                 (let loop ((datum (read)))
>                   (if (eof-object? datum) '()
>                     (cons datum (loop (read)))))))))
>
> and an 'include' reader-ctor is set up as
>         (define-reader-ctor 'include read-all-as-a-begin-expr)
> The following form
>         #,(include "foo.scm")
>
> appears to have the same semantics as
>         (include "foo.scm")
> in Gambit.

In Gambit, the form (include "foo.scm") operates at macro-expansion
time, after *all* the source code in the file has been read by the
reader.  Your implementation, i.e. #,(include "foo.scm"), is not
completely equivalent because it is done at read-time (for example if
"foo.scm" contains #,(define-reader-ctor 'bar ...) then in your
implementation it is valid to have a #,(bar ...) after the #,(include
"foo.scm") in the same file).  This is exactly the kind of problem I
was hinting at in my previous message...

Marc