The type system seems to have changed in OCaml 1.06.  The following code
no longer compiles (it compiled in ocaml-1.05):

    type x = x option

Here's the complaint:

% ocamlc -c x.ml
File "x.ml", line 1, characters 4-17:
The type abbreviation x is cyclic

This doesn't seem like a problem with the type theory, since the type
"x" should probably be isomorphic to the natural numbers.  Is there a
reason for the failure?

-- 
Jason Hickey                    Email: jyh@cs.cornell.edu
Department of Computer Science  Tel: (607) 255-4392
Cornell University