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
126
127
128
129

use crate::{
    DependentJoint, Distribution, IndependentJoint, RandomVariable, SampleableDistribution,
};
use rand::prelude::*;
use std::{
    fmt::Debug,
    marker::PhantomData,
    ops::{BitAnd, Mul},
};

#[derive(Clone, Debug)]
pub struct TransformedDistribution<D, T, U, V>
where
    D: Distribution<Value = T, Condition = U>,
    T: RandomVariable,
    U: Clone + Debug + Send + Sync,
    V: RandomVariable,
{
    distribution: D,
    phantom: PhantomData<V>,
}

impl<D, T, U, V> TransformedDistribution<D, T, U, V>
where
    D: Distribution<Value = T, Condition = U>,
    T: RandomVariable,
    U: Clone + Debug + Send + Sync,
    V: RandomVariable,
{
    pub fn new(distribution: D) -> Self {
        Self {
            distribution,
            phantom: PhantomData,
        }
    }
}

impl<D, T, U, V> Distribution for TransformedDistribution<D, T, U, V>
where
    D: Distribution<Value = T, Condition = U>,
    T: RandomVariable,
    U: RandomVariable,
    V: RandomVariable,
{
    type Value = (T, V);
    type Condition = (U, V);

    fn p_kernel(
        &self,
        x: &Self::Value,
        theta: &Self::Condition,
    ) -> Result<f64, crate::DistributionError> {
        self.distribution.p_kernel(&x.0, &theta.0)
    }
}
pub trait TransformableDistribution: Distribution + Sized {
    /// .
    ///
    /// # Examples
    ///
    /// ```
    /// // Example template not implemented for trait functions
    /// ```
    fn transform<V>(self) -> TransformedDistribution<Self, Self::Value, Self::Condition, V>
    where
        V: RandomVariable;
}

impl<D, T, U1> TransformableDistribution for D
where
    D: Distribution<Value = T, Condition = U1>,
    T: RandomVariable,
    U1: RandomVariable,
{
    fn transform<V>(self) -> TransformedDistribution<Self, Self::Value, Self::Condition, V>
    where
        V: RandomVariable,
    {
        TransformedDistribution::<Self, Self::Value, Self::Condition, V>::new(self)
    }
}

impl<D, T, U, V, Rhs, TRhs> Mul<Rhs> for TransformedDistribution<D, T, U, V>
where
    D: Distribution<Value = T, Condition = U>,
    T: RandomVariable,
    U: RandomVariable,
    V: RandomVariable,
    Rhs: Distribution<Value = TRhs, Condition = (U, V)>,
    TRhs: RandomVariable,
{
    type Output = IndependentJoint<Self, Rhs, (T, V), TRhs, (U, V)>;

    fn mul(self, rhs: Rhs) -> Self::Output {
        IndependentJoint::new(self, rhs)
    }
}

impl<D, T, U, V, Rhs, URhs> BitAnd<Rhs> for TransformedDistribution<D, T, U, V>
where
    D: Distribution<Value = T, Condition = U>,
    T: RandomVariable,
    U: RandomVariable,
    V: RandomVariable,
    Rhs: Distribution<Value = (U, V), Condition = URhs>,
    URhs: RandomVariable,
{
    type Output = DependentJoint<Self, Rhs, (T, V), (U, V), URhs>;

    fn bitand(self, rhs: Rhs) -> Self::Output {
        DependentJoint::new(self, rhs)
    }
}

impl<D, T, U, V> SampleableDistribution for TransformedDistribution<D, T, U, V>
where
    D: SampleableDistribution<Value = T, Condition = U>,
    T: RandomVariable,
    U: RandomVariable,
    V: RandomVariable,
{
    fn sample(
        &self,
        theta: &Self::Condition,
        rng: &mut dyn RngCore,
    ) -> Result<Self::Value, crate::DistributionError> {
        Ok((self.distribution.sample(&theta.0, rng)?, theta.1.clone()))
    }
}