Crate roll 

A dice roller library for tabletop RPGs.

Supports standard dice notation (e.g. 2d10+4), advantage/disadvantage, keep-highest/lowest (4d6kh3), and Monte Carlo / exact probability estimation.

Examples

use roll::{parse_expr, Modifier};

let expr = parse_expr("2d10+4").unwrap();
assert_eq!(expr.flat_bonus, 4);
assert_eq!(expr.modifier, Modifier::None);
assert_eq!(expr.groups.len(), 1);
assert_eq!(expr.groups[0].count, 2);
assert_eq!(expr.groups[0].sides, 10);

Structs

DiceExpr

A parsed dice expression such as adv 2d10+1d4+3.

DiceGroup

A group of identical dice, e.g. 2d10 means 2 ten-sided dice.

RollStats

Theoretical statistics for a dice expression (min, max, mean).

Enums

Keep

Keep rule applied to a dice group after rolling.

Modifier

Modifier applied to a dice roll (advantage, disadvantage, or none).

ParseError

Error type for dice expression parsing failures.

Functions

compute_distribution

Run a Monte Carlo simulation and return the count of each result value.

estimate_probability

Estimate the probability of rolling at least target using Monte Carlo simulation.

exact_probability

Compute the exact probability of rolling at least target via polynomial convolution.

format_rolls

Format roll results as a human-readable string like [3, 5] + [2].

parse_expr

Parse a dice expression string into a DiceExpr.

render_distribution

Render a probability distribution histogram as a string.

roll_once

Roll the dice once, returning the total and the kept dice per group.

roll_stats

Compute theoretical min, max, and mean for a DiceExpr.

roll_value

Roll and return just the final value, applying advantage/disadvantage.

roll_verbose

Roll with detailed output, returning the total and a human-readable breakdown.