On Mon, 2006-07-10 at 16:25 -0700, brogoff wrote:

> The restriction on polymorphism in mutually recursive class
> definitions makes the idea unworkable. Any possibility that restriction will be
> lifted?

I don't believe there is such a restriction: the problem is
when you introduce other types such as variants which must
recurse with class types, there's no support for

type class t1 = ..
and t2 = [`X ..]

etc. The solution, using extra parameters and open
recursion, followed by closure of the recursions,
works but is vastly too messy to encode by hand if there
are more than a couple of parameters needed. This really
does need to be automated in the special case where
you're only opening the types so you can later close them.

In general, for incremental type building, you need to retain
the open types.. and it isn't clear if there's any way
to make it tractable (syntactically I mean).

Unfortunately .. the easiest kind of solution is to write
a code generator in Python or Perl .. this kind of polymorphism
is not exactly desirable .. ;(

Can MetaOcaml can handle this better?

-- 
John Skaller <skaller at users dot sf dot net>
Felix, successor to C++: http://felix.sf.net