SRFIs 11, 12, and 15

Chicken currently implements the SRFIs 11 (let-values and let-values*),
12 (exceptions), and 15 (fluid-let), but (use srfi-11), (use srfi-12),
and (use srfi-15) and their syntactic analogues throw errors rather than
silently doing nothing.


-- 
Cash registers don't really add and subtract;           John Cowan
        they only grind their gears.                    cowan@xxxxxxxx
But then they don't really grind their gears, either;   
http://www.reutershealth.com
        they only obey the laws of physics.  --Unknown