crumble

A Rust implementation of the Strudel pattern language for algorithmic music.

Strudel is a live coding environment that implements the TidalCycles pattern language. This crate provides the core pattern engine in Rust.

Core Concepts

• Pattern: A function from time to events. Patterns can be transformed, combined, and queried to produce musical events.
• Hap: An event (happening) with a value active during a timespan.
• Fraction: Rational numbers for precise timing within cycles.
• TimeSpan: An arc of time with begin and end points.

Usage

use crumble::prelude::*;

// Create a simple sequence
let pat = sequence(vec![pure(1), pure(2), pure(3), pure(4)]);

// Query the first cycle
let events = pat.first_cycle();
assert_eq!(events.len(), 4);

// Transform patterns
let fast_pat = pat.fast(Fraction::from_integer(2));  // Play twice as fast
let slow_pat = pat.slow(Fraction::from_integer(2));  // Play half as fast

// Stack patterns (play simultaneously)
let stacked = stack(vec![
    pure("kick"),
    sequence(vec![pure("hihat"), pure("hihat")]),
]);

// Euclidean rhythms
let rhythm = euclid(3, 8, "snare");  // 3 hits over 8 steps

// Signal patterns
let lfo = sine();  // 0-1 sine wave over each cycle
let scaled = range(200.0, 800.0, lfo);  // Scale to 200-800

Pattern Constructors

• pure(value) - A single value that repeats once per cycle
• silence() - Empty pattern (no events)
• sequence(pats) / fastcat(pats) - Concatenate patterns within one cycle
• cat(pats) / slowcat(pats) - Concatenate patterns, one per cycle
• stack(pats) - Play patterns simultaneously
• euclid(pulses, steps, value) - Euclidean rhythm generator

Pattern Transformations

• .fast(n) - Speed up by factor n
• .slow(n) - Slow down by factor n
• .early(t) - Shift earlier in time
• .late(t) - Shift later in time
• .rev() - Reverse within each cycle
• .fmap(f) - Apply function to values
• .every(n, f) - Apply transformation every n cycles
• .ply(n) - Repeat each event n times
• .superimpose(f) - Layer transformation on top

Signal Patterns

Continuous patterns for modulation:

• saw() - Sawtooth wave (0 to 1)
• sine() - Sine wave (0 to 1)
• cosine() - Cosine wave (0 to 1)
• tri() - Triangle wave (0 to 1)
• square() - Square wave (0 or 1)
• range(min, max, pat) - Scale signal to range

License

AGPL-3.0 (same as Strudel)