> The question is: if this behavior was completely outlawed, and either you
> couldn't build up circular lists/recursive data structures of this type at
> all, or had to call special functions (List.circularize, say), to create
> them, would this be a signifigant problem?  Does anyone actually use this
> construct, and if so, for what?

This is the case in SML: you need to go through a `ref' cell in order to
create a cycle.  This has very rarely been presented as
a serious limitation.  OCaml's trick is occasionally useful, but I don't
think anybody would lose her sleep over it.


        Stefan