Need letrec

[zaphod.mps.ohio-state.edu!uwm.edu!ux1.cso.uiuc.edu!ux1.cso.uiuc.edu!cs325ec@think.com]

	If anyone has some time, could you take the time to mail
	me a letrec funtion definition (or macro) that will work
	on the simplest of scheme implementations... i.e. only
	+,- etc., null? car, cons etc.

	Thanks

	-Greg