The distinction between `make-parameter' and `make-mutable-parameter'
is a reasonable compromise.

MzScheme can't currently support `make-mutable-parameter'. I imagine a
revision in the near future that will allow it, but I wonder what kinds
of tasks make mutable parameters useful. (No doubt I've asked before,
but the answer didn't stick. In the future, I can consult the archive
of this list. :)

The body of a `parameterize' is not in tail position, right?

Typo in `make-parameter' example: it uses `make-mutable-parameter'.

Matthew