Module programinduction::pcfg

source ·
Expand description

(representation) Probabilistic context-free grammar without bound variables or polymorphism.

Examples

use polytype::tp;
use programinduction::{Task, pcfg::{task_by_evaluation, Grammar, Rule}};

fn evaluator(name: &str, inps: &[i32]) -> Result<i32, ()> {
    match name {
        "0" => Ok(0),
        "1" => Ok(1),
        "plus" => Ok(inps[0] + inps[1]),
        _ => unreachable!(),
    }
}

let g = Grammar::new(
    tp!(EXPR),
    vec![
        Rule::new("0", tp!(EXPR), 1.0),
        Rule::new("1", tp!(EXPR), 1.0),
        Rule::new("plus", tp!(@arrow[tp!(EXPR), tp!(EXPR), tp!(EXPR)]), 1.0),
    ],
);

// task: the number 4
let target = 4;
let task = task_by_evaluation(&evaluator, &target, tp!(EXPR));

// solution:
let expr = g.parse("plus(1, plus(1, plus(1,1)))").unwrap();
assert!(task.oracle(&g, &expr).is_finite())

Structs

  • AppliedRule
    Identifies a rule by its location in grammar.rules.
  • EstimationParams
    Parameters for PCFG parameter estimation.
  • GeneticParams
    Parameters for PCFG genetic programming (GP).
  • Grammar
    (representation) Probabilistic context-free grammar. Currently cannot handle bound variables or polymorphism.
  • Rule
    A PCFG rule specifies a production that can happen for a particular nonterminal.

Enums

Functions

  • task_by_evaluation
    Create a task based on evaluating a PCFG sentence and comparing its output against data.