[plt-scheme] How is letrec different from letrec* in its use?

Shriram Krishnamurthi <sk at cs.brown.edu> writes:

> These threads (we had a recent flare-up about LOCAL, as
> some might recall) point to the worst thing about Old
> Scheme: not only did they leave the semantics undefined,
> they ALSO didn't have the courtesy to provide a reference
> compiler that actually produced unexpected output, thereby
> compounding confusion (resulting in unknown unknowns).

Where's the reference implementation that gets this right
for R6RS?  Neither plt-r6rs nor larceny signal an error.
Ikarus signals the wrong error, but doesn't signal an error
if you replace `+' with `cons'.

-- 
Alex