Detecting kawa/scheme implementation for conditional require

[David O'Callaghan <david dot ocallaghan at cs dot tcd dot ie>]

Hi,

I'm wondering if there's some way to portably detect the scheme 
implementation in use. Basically, I want to write scheme code that works 
in both PLT MzScheme and Kawa (mainly because I find the PLT DrScheme 
environment pleasant to use). In some code I'm working on I need to 
include the srfi-69 support for the Kawa version, but (require 'srfi-69) 
is not acceptable to MzScheme.

I want to be able to do something like:

(if (eq? scheme-version 'kawa-1.8)
   (require 'srfi-69))

I can define scheme-version in a wrapper module which is distinct for 
each implementation, but "require" must appear at the top level. Does 
anyone have a suggestion?

Thanks,

David