> One issue I ran into was syntactic.  How would you write:
>  if 'A' <= c && c <= 'Z' then ...
> where c is a char, without polymorphic comparison, and without more
radical changes such as type
> classes?  

SML's ad-hoc polymorphism. Would also be nice if you could fill out the
primitive types with 32-bit floats, ints of different sizes and so on.

Also, would be excellent if you could make the compiler agnostic with regard
to the run-time representation of these types so a new back-end could unbox
all primitive types.

Cheers,
Jon.