More implementation details :)

[Rici Lake <lua@...>]

Speaking of immutable objects and interning, there is an interesting
intermediate possibility: lazy interning.

Basically, an immutable object can be interned when an attempt is made 
to
use it as a table key (and possibly when any equality comparison is 
done).
This might be useful, for example, for immutable vectors representing 
points,
rectangles, or colours.

This wouldn't work with character strings, without taking some care, 
because
the C API relies on character strings not moving around. However, it 
would
work on an immutable object whose elements could only be accessed 
through
some API call; an immutable tuple of full Lua objects would have to be 
of
this form.

R.