[plt-scheme] Re: current-eval is now ready to receive anything...

From: Ryan Culpepper (ryan_sml at yahoo.com)
Date: Mon Mar 5 15:09:19 EST 2007

--- "Paulo J. Matos" <pocm at soton.ac.uk> wrote:

> Sorry... pressed Send,  when I should have pressed Save...
> The message continues below...
> On 3/5/07, Paulo J. Matos <pocm at soton.ac.uk> wrote:
> > Hi all,
> >
> > By preparing current-eval to receive more than just
> syntax-objects as
> > stated in docs (which I quoted in my last post but
> mis-interpreted)
> > can I know before hand which things may be passed to current-eval
> > besides what the user types in and their type?
> > My guess is that when the user types something it is sent in the
> form
> > of syntax object to current-eval, except the s-expr
> (current-namespace (module->namespace 'test))
> Up until now I was not able to find any exception to this rule.
> Is there anything more I should know?

The module-name-resolver calls the current evaluator on the compiled
code for a module the first time a module is required. And the 'eval'
procedure just passes along whatever it is given:

  (define old-evaluator (current-eval))
  (define (evaluator x)
    (cond [(and (syntax? x) (compiled-expression? (syntax-e x)))
           (display "evaluating compiled code wrapped in syntax\n")]
          [(syntax? x)
           (display "evaluating syntax\n")]
          [(compiled-expression? x) (display "evaluating compiled
          [else (display "evaluating S-expression\n")])
    (old-evaluator x))
  (begin (current-eval evaluator)
         ;; the module-name-resolver calls eval
         ;; on the contents of the .zo file
         (require (lib "cmdline.ss"))
         ;; 'eval' just passes argument along
         (void (eval '(lambda (x) x)))
         (void (eval (compile '(lambda (x) x)))))


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