Introduce syntax like:
iface animal { ... }
class cat implements animal { ... }
to allow classes to implement ifaces. Casting classes to ifaces
is *not* yet supported. ifaces that a class implements are not
yet included in metadata.
The syntax is subject to change, and may go away completely if we
decide to use duck typing to relate classes with ifaces (see
http://smallcultfollowing.com/babysteps/blog/2012/04/10/declared-vs-duckish-typing/ )
get_with_default (nee from_maybe) => get_default
with_option (nee maybe) => map_default
with_option_do (nee may) => iter
As per discussion of 21be1379d561b6679a8a2ea47dce88f948c5acca
Most could use the each method, but because of the hack used to
disambiguate old- and new-style loops, some had to use vec::each.
(This hack will go away soon.)
Issue #1619
from_maybe => get_with_default
maybe => with_option
may => with_option_do
I know these names are kind of ridiculous, but it's the best I could think of.
Feel free to bikeshed. Closes#2081
