Re: Module example

[Keith Wright <kwright@tiac.net>]

> From: thi <ttn@netcom.com>
> 
> (define f-there
>   (variable-ref (module-variable (resolve-module '(there)) 'f)))
> 
> (f-there 3) => 9
> (f 3) => 6
> 
> this is not in any manual because the module system is slated for
> redesign.  although it's been pointed out that implementation details
> should not be made available, i still am wondering about the new
> module system spec.  ie, will `module-variable' and `resolve-module'
> still be around?
> 

I hope not.  "First class variables" and procedures to turn arbitrary
symbols computed at run-time into variables both throw a monkey wrench
(spanner) into the Scheme system of lexical binding, and are impossible
to compile effectively.  If it must be done the appropriate syntax is:

      (eval 'f module-envirionment)

this makes it clear that you are invoking the entire
compiler/interpreter, and not just loading a value from an address.

The module system should not require anything like this.  Instead
there should be a special syntax for importing a module while
systematically re-naming its exported variables.  This should be done
in such a way that a straight-forward scan of the source code of the
program and the module will yield a list of all identifiers that can
be bound to a given storage location (in a given lexical scope and
environment etc...).

-- 
     --Keith

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