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Re: vm branch now uses vm repl by default

From: Ludovic Courtès
Subject: Re: vm branch now uses vm repl by default
Date: Tue, 09 Sep 2008 10:41:41 +0200
User-agent: Gnus/5.11 (Gnus v5.11) Emacs/22.3 (gnu/linux)


Andy Wingo <address@hidden> writes:

> I've enabled the VM repl by default on the vm branch. Here's a brief
> annotated tour:
>     $ ./pre-inst-guile
>     Guile Scheme interpreter 0.5 on Guile 1.9.0
>     Copyright (C) 2001-2008 Free Software Foundation, Inc.
>     Enter `,help' for help.


> Late-variable-ref looks at a cell in the object vector. If it is a
> symbol, it is resolved relative to the module that was current when the
> program was made. The object cell is then replaced with the resulting
> resolved variable. Here we see that objects 0 and 1 were already
> resolved. Object 2 is just the constant, #:bar.

Aaah, nice!  So, previously, there was `variable-ref':

 -- Instruction: variable-ref
     Dereference the variable object which is on top of the stack and
     replace it by the value of the variable it represents.

Now, there's also a vector associated with each closure to store
references to global variables, right?  Looks better!

(Hint: the doc is outdated.  :-))

>     scheme@(guile-user)> ,option interp #t
>     scheme@(guile-user)> ,option
>     trace     #f
>     interp    #t
> Here we tell the repl that, given the option, we prefer to interpret
> rather than compile. Of course, if the current language doesn't support
> compilation, we always interpret.

That means good old `CEVAL ()' is used, right?

When that is the case, one can still use `{eval,debug}-options', right?

It'd be nice if we could find a way to "do something" with the
`current-reader' fluid at compilation time, like detecting top-level
`(fluid-set! current-reader ...)' statements and use that to switch the
compiler's reader (hacky...).

Thanks for the good news!


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