Struct PermutationPrior 

pub struct PermutationPrior { /* private fields */ }

Fisher–Yates / Lehmer-code uniform prior over permutations of 0..n.

Position i samples a rank at perm#i, uniform over the n−i values not yet used (a Usize in 0..n−i); the rank sequence decodes to a permutation against the shrinking available-value list. This coincides site-for-site with Permutation::to_trace’s Lehmer encoding, so scoring an existing genome’s trace under replay finds every site with matching semantics, and:

• every model execution decodes to a valid permutation (density exactly 1/n!), and
• under single-site MH, resampling one rank always decodes to a different valid permutation — the rank encoding is what makes single-site moves live (a raw value encoding would turn every single-site change into a duplicate and freeze the chain).

Implementations

impl PermutationPrior

pub fn new(n: usize) -> Self

Uniform prior over permutations of 0..n.

Trait Implementations

impl Clone for PermutationPrior

fn clone(&self) -> PermutationPrior

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for PermutationPrior

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl GenomePrior for PermutationPrior

type Genome = Permutation

The genome type this prior generates.

fn model(&self) -> Model<Permutation>

The generative program p(x).

fn trace_of(&self, genome: &Self::Genome) -> Trace

Encode a genome as a trace under this prior’s address scheme — the inverse direction of running Self::model. The default delegates to the genome’s canonical TraceGenome::to_trace encoding, which is correct whenever the prior samples exactly the canonical sites (all the vector priors here). Priors with their own generative scheme — e.g. ArithmeticGrammarPrior’s tree-path grammar — override this so that scoring, weighted traces, and chain warm-starts work for any genome the prior can express.