Struct ScoreGivenTrace 

pub struct ScoreGivenTrace {
    pub base: Trace,
    pub trace: Trace,
}

Handler for scoring a model given a complete trace of fixed choices.

ScoreGivenTrace computes log-probability of a model execution where all random choices are predetermined. No sampling occurs - values are looked up from the base trace and their log-probabilities computed. Essential for MCMC acceptance ratios, importance sampling, and model comparison.

Example:

// Create a complete trace
let mut rng = StdRng::seed_from_u64(42);
let (_, complete_trace) = runtime::handler::run(
    PriorHandler { rng: &mut rng, trace: Trace::default() },
    sample(addr!("x"), Normal::new(0.0, 1.0).unwrap())
);

// Score under different model parameters  
let (value, score_trace) = runtime::handler::run(
    ScoreGivenTrace {
        base: complete_trace,
        trace: Trace::default()
    },
    sample(addr!("x"), Normal::new(1.0, 2.0).unwrap()) // Different parameters
);

assert!(score_trace.total_log_weight().is_finite());

Fields

base: Trace

Base trace containing the fixed choices to score.

trace: Trace

New trace to accumulate log-probabilities.

Trait Implementations

impl Handler for ScoreGivenTrace

fn on_sample_f64(&mut self, addr: &Address, dist: &dyn Distribution<f64>) -> f64

Handle an f64 sampling operation (continuous distributions).

fn on_sample_bool( &mut self, addr: &Address, dist: &dyn Distribution<bool>, ) -> bool

Handle a bool sampling operation (Bernoulli).

fn on_sample_u64(&mut self, addr: &Address, dist: &dyn Distribution<u64>) -> u64

Handle a u64 sampling operation (Poisson, Binomial).

fn on_sample_usize( &mut self, addr: &Address, dist: &dyn Distribution<usize>, ) -> usize

Handle a usize sampling operation (Categorical).

fn on_observe_f64( &mut self, _: &Address, dist: &dyn Distribution<f64>, value: f64, )

Handle an f64 observation operation.

fn on_observe_bool( &mut self, _: &Address, dist: &dyn Distribution<bool>, value: bool, )

Handle a bool observation operation.

fn on_observe_u64( &mut self, _: &Address, dist: &dyn Distribution<u64>, value: u64, )

Handle a u64 observation operation.

fn on_observe_usize( &mut self, _: &Address, dist: &dyn Distribution<usize>, value: usize, )

Handle a usize observation operation.

fn on_factor(&mut self, logw: f64)

Handle a factor operation.

fn finish(self) -> Trace

Finalize the handler and return the accumulated trace.