Re: Status Summary; next steps

"Michael Lazzaro" <[email protected]> wrote
> I'm trying to think of a counterexample, in which you have a context
> that _cannot_ be represented as a "type" according to this very broad
> definition.  I don't think it should be possible, is it?  If it _is_
> possible, does that represent a flaw/limitation of the perl6 "types"?

Let us imagine that an object can tell us that it will be destroyed
as a result of the assignment (we don't have ref-counts, but
some variables are scoped lexically). Now imagine that the
output object is expensive to create: but that the current
object (which will be destroyed as a result of the assignment)
can be cheaply modified. There might be some optimization
potential here.

Perhaps an example will clarify my thoughts

  my $big_heavy_object = Foo.new;
  $big_heavy_object = add($big_heavy_object, $bar);

If the context provides access to the lvalue, then it
may be possible to optimize. Effectively, we have the
information to create an implicit C<+=> operator. The
add method should be able to utilize the fact that it
can recycle the old lvalue.

If the old-lvalue is available in the context, then the context
is more than a type.


Dave.