From: Sin-Yaw Wang
Subject: Re: Foreign Functions (was Re: Why lisp failed in the marketplace)
Date: 
Message-ID: <33149519.2FE7@acm.org>
Holger Schauer wrote:
> So, would you say that it is not possible to define such a standard
> interface because it would require uniform implementation details ?
> Or would you say it is possible but not very probable that
> lisp-vendors (free lisp vendors alike) can and will standarize on
> such an interface ?

I thought hard for this problem last time I wrote my Scheme interpretor
and gave up.

It is possible to define a Scheme->C interface, that a Scheme function
can call a C function.  I am not sure it is possible to define a
C->Scheme interface at the same time.  The stumbling block is the
continuation, a concept really does not exist in C.

Imagine a C function calling a user-level Scheme funciton that calls
call/cc.  Later, another Scheme function invokes that continuation.

I just couldn't get this right.  Will appreciate whoever can shed some
lights here.

-- 
Sin-Yaw Wang, ······@acm.org
http://www.concentric.net/~sinyaw/