> But the other thing you miss is that even in ocaml, environments
> are NOT immutable: there are mutable fields, and thus mutable
> data structures like Hashtbl. The fact is, some things are easier
> to express in a stateful manner than a functional one.

Strictly speaking, environments in Caml ARE immutable: there is no way
to change the binding of an identifier. What can be mutated are
designated sub-parts of values bound to identifiers.

Pierre Weis

INRIA, Projet Cristal, Pierre.Weis@inria.fr, http://cristal.inria.fr/~weis/