add C.OpEval which contains c-- primitive optimizations
add C.OpEval which contains c-- primitive optimizations

darcs-hash:20070531071354-1a7c6-2a5242d2fcb27f35ebc438c504a89cae006aac18

kirbyfan64/jhc,kirbyfan64/jhc,kirbyfan64/jhc,kirbyfan64/jhc