I've been reading the blogs about rust and this closure for example made me wonder:

```
fn each<E>(t: &Tree<E>, f: &fn(&E) -> bool) {
if !f(&t.elem) {
return;
}
for t.children.each |child| { each(child, f); }
}
```

why couldn't it be:

```
each<E>(t: &Tree<E>, f: &(&E) -> bool) {
if !f(&t.elem) {
return;
}
for t.children.each |child| { each(child, f); }
}
```

Maybe i'm missing something on the class system that would prevent this.