1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
use std::{rc::Rc, cell::RefCell};
pub struct Context<E>(pub Rc<RefCell<Option<E>>>)
where
E: Effect;
impl<E> Default for Context<E>
where
E: Effect,
{
fn default() -> Self {
Context(Rc::new(RefCell::new(None)))
}
}
impl<E> Clone for Context<E>
where
E: Effect,
{
fn clone(&self) -> Self {
Context(self.0.clone())
}
}
impl<E> Context<E>
where
E: Effect,
{
pub fn take<Part>(&self) -> Option<Part>
where
E: Composable<Part>,
{
E::take(self)
}
}
pub trait Effect {
type Input;
}
pub trait Composable<Part>
where
Self: Sized + Effect,
{
fn take(output: &Context<Self>) -> Option<Part>;
}