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
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
use core::marker::PhantomData;

use crate::{
    build::Builder,
    effect::{Adapters, Effect, ObjSafe},
    hkt::Marker,
    Walk, Walker, WalkerTypes,
};

#[inline(always)]
#[allow(clippy::type_complexity)]
pub fn transform<'a, 'ctx: 'a, B: Builder<'ctx, E> + 'a, W: Walker<'ctx, E> + 'a, E: Effect>(
    seed: B::Seed,
    walker: W,
) -> ObjSafe<'a, (Result<B::Value, B::Error>, Result<W::Output, W::Error>), E> {
    B::from_seed(seed)
        .as_ctx_for(
            #[inline(always)]
            move |builder, _| (walker.walk(builder.as_visitor()), PhantomData),
        )
        .then(|(builder, walker_result), _| {
            builder
                .build()
                .map(|builder_result| (builder_result, walker_result))
                .into()
        })
        .into()
    // B::from_seed(seed).map_with(walker, |builder, walker| walker.walk(builder.as_visitor()));

    // E::wrap(async {
    //     // Create builder from seed value;
    //     let mut builder = B::from_seed(seed).await;
    //
    //     // Walk the walker with the builder as the visitor.
    //     let walker_result = walker.walk(builder.as_visitor()).await;
    //
    //     // Finish building the value.
    //     let builder_result = builder.build().await;
    //
    //     (builder_result, walker_result)
    // })
}

/// For use in a lens.
pub struct Projection<T, B, U, M> {
    value: T,
    builder: B,
    _marker: Marker<(U, M)>,
}

// #[allow(clippy::type_complexity)]
// impl<T, B, U: Send + Sync, M> Projection<T, B, U, M> {
//     pub fn project_ref<'a, E: Effect>(
//         &'a self,
//     ) -> Future<
//         'a,
//         (
//             Result<&'a U, B::Error>,
//             Result<<<&'a T as Walk<'>>::Walker as WalkerTypes>::Output, <&'a T as WalkerTypes>::Error>,
//         ),
//         E,
//     >
//     where
//         &'a T: Walk<'a, M, E>,
//         B: Clone + Builder<'a, E, Value = &'a U>,
//     {
//         let walker = self.value.into_walker();
//         let mut builder = self.builder.clone();
//
//         E::wrap(async {
//             let result = walker.walk(builder.as_visitor()).await;
//
//             (builder.build().await, result)
//         })
//     }
//
//     pub fn project_mut<'a, E: Effect>(
//         &'a mut self,
//     ) -> Future<
//         'a,
//         (
//             Result<&'a mut U, B::Error>,
//             Result<<&'a mut T as WalkerTypes>::Output, <&'a mut T as WalkerTypes>::Error>,
//         ),
//         E,
//     >
//     where
//         &'a mut T: Walk<'a, M, E>,
//         B: Clone + Builder<'a, E, Value = &'a mut U>,
//     {
//         let walker = self.value.into_walker();
//         let mut builder = self.builder.clone();
//
//         E::wrap(async {
//             let result = walker.walk(builder.as_visitor()).await;
//
//             (builder.build().await, result)
//         })
//     }
//
//     pub fn project<'a, E: Effect>(
//         self,
//     ) -> Future<
//         'a,
//         (
//             Result<U, B::Error>,
//             Result<<T as WalkerTypes>::Output, <T as WalkerTypes>::Error>,
//         ),
//         E,
//     >
//     where
//         T: Walk<'a, M, E> + 'a,
//         M: 'a,
//         B: Clone + Builder<'a, E, Value = U> + 'a,
//     {
//         let walker = self.value.into_walker();
//         let mut builder = self.builder.clone();
//
//         E::wrap(async {
//             let result = walker.walk(builder.as_visitor()).await;
//
//             (builder.build().await, result)
//         })
//     }
// }