modppl 0.3.0

a experimental library for probabilistic programming in Rust.
Documentation 
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use rand::rngs::ThreadRng;
use super::Distribution;
use rand_distr::{
    Distribution as _,
    Poisson as PoissonSampler
};


/// Poisson distribution type
pub struct Poisson { }

/// Instantiation of the poisson distribution
pub const poisson: Poisson = Poisson { };

impl Distribution<i64,f64> for Poisson {
    fn logpdf(&self, k: &i64, rate: f64) -> f64 {
        (*k as f64)*rate.ln() - rate - (1..=*k).map(|v| (v as f64).ln()).sum::<f64>()
    }

    fn random(&self, rng: &mut ThreadRng, rate: f64) -> i64 {
        let poisson_sampler = PoissonSampler::new(rate).ok().unwrap();
        poisson_sampler.sample(rng) as i64
    }
}