add initial reference invalidation

+ Makes vec example actually memory safe, which is cool

+ Specify owner > sub relationships with ">" in closure parameter
  lists, uses the same group idea as closure calls

+ Relies on users implementing functions in a consistent manner,
  since you can kind of do whatever with pointers. Presumably
  there would be a stdlib of vec/map/set etc. which applications
  could then use and by proxy be memory safe. Although some more
  checks wouldn't hurt, I suppose?

+ Not sure I like having reference invalidation be 'just a move',
  seems to work alright but the semantics of it are a bit muddy.

1 files changed, 1 insertions, 1 deletions

diff --git a/examples/vec.fwd b/examples/vec.fwd
index 6950c2a..75c5b2e 100644
--- a/examples/vec.fwd
+++ b/examples/vec.fwd
@@ -75,7 +75,7 @@ append_vec(vec v, i64 e, (vec) ok)
 	ok(v);
 }
 
-at_vec(vec v, u64 i, (vec, &i64) ok)
+at_vec(vec v, u64 i, (vec > &i64) ok)
 {
 	v => [n => n, s => s, buf => buf];
 	guard(i < n) => {