Uniform deriving

Uniform deriving.

// Uniform requests use the existing producer registry and real builtins.

@derive_for(Marker)
fn marker(info) -> Syntax<.Items> {
    return quote items { impl ${info.ref} { fn marker(self) -> int { 37 } } }
}

@derive(Clone)
struct User { id: int, name: str } deriving Eq, Hash
let user = User { id: 1, name: "Ada" }
print(user.eq(User { id: 1, name: "Ada" }))
print(user.eq(User { id: 1, name: "Bea" }))
print(user.clone().name)
print(user.hash())
print(user.eq(User { id: 1, name: "Ada" }) && user.hash() == User { id: 1, name: "Ada" }.hash())
print(user.hash() != User { id: 2, name: "Ada" }.hash())

struct Counter(value: int) { fn read(self) -> int { self.value } } deriving Clone
print(Counter.new(7).clone().read())

enum State(Ready, Busy) deriving Eq, Marker
let state: State = .Ready
print(state.marker())
print(state.eq(State::Ready))
print(state.eq(State::Busy))

enum Shape { Empty, Point(int), Pair(int, str), Rect { width: int, height: int } } deriving Eq
print(Shape::Pair(7, "Ada").eq(Shape::Pair(7, "Ada")))
print(Shape::Pair(7, "Ada").eq(Shape::Pair(7, "Bea")))
print(Shape::Rect { width: 2, height: 3 }.eq(Shape::Rect { width: 2, height: 4 }))

struct Envelope<T: core::cmp::Eq + core::hash::Hash> { value: T } deriving Eq, Hash
let nested = Envelope { value: user }
print(nested.hash())
print(nested.eq(Envelope { value: User { id: 1, name: "Ada" } }))

struct Empty {} deriving Eq, Hash
print(Empty {}.hash())
struct Text { value: str } deriving Eq, Hash
print(Text { value: "ação" }.hash())
print(Text { value: "" }.hash())

newtype Id(int) deriving Eq, Hash
print(Id.new(8).hash())
print(Id.new(8).eq(Id.new(9)))

struct Defaults { count: int } deriving Default
print(Defaults.default().count)