Timing with at

Every step has a duration. By default, sounds emit at the very start of that duration. at changes when within the step sounds fire -- giving you sub-step rhythmic control without adding more steps.

The Basics

at drains the entire stack and stores the values as timing offsets. Each value is a fraction of the step duration: 0 = start, 0.5 = halfway, 1.0 = next step boundary.

0.5 at kick s .         ;; kick at the midpoint

Push multiple values before calling at to get multiple emits from a single .:

0 0.5 at kick s .       ;; two kicks: one at start, one at midpoint
0 0.25 0.5 0.75 at hat s .   ;; four hats, evenly spaced

The deltas persist across multiple . calls until clear or a new at:

0 0.5 at
kick s .                ;; 2 kicks
hat s .                 ;; 2 hats (same timing)
clear
snare s .               ;; 1 snare (deltas cleared)

Cross-product: at Without arp

Without arp, deltas multiply with polyphonic voices. If you have 3 notes and 2 deltas, you get 6 emits -- every note at every delta:

0 0.5 at
c4 e4 g4 note sine s .   ;; 6 emits: 3 notes x 2 deltas

This is a chord played twice per step.

1:1 Pairing: at With arp

arp changes the behavior. Instead of cross-product, deltas and arp values pair up 1:1. Each delta gets one note from the arpeggio:

0 0.33 0.66 at
c4 e4 g4 arp note sine s .   ;; c4 at 0, e4 at 0.33, g4 at 0.66

If the lists differ in length, the shorter one wraps around:

0 0.25 0.5 0.75 at
c4 e4 arp note sine s .       ;; c4, e4, c4, e4 at 4 time points

This is THE key distinction. Without arp: every note at every time. With arp: one note per time slot.

Generating Deltas

You rarely type deltas by hand. Use generators:

Evenly spaced via .,:

0 1 0.25 ., at hat s .        ;; 0 0.25 0.5 0.75 1.0

Euclidean distribution via euclid:

3 8 euclid at hat s .         ;; 3 hats at positions 0, 3, 5

Random timing via gen:

{ 0.0 1.0 rand } 4 gen at hat s .   ;; 4 hats at random positions

Geometric spacing via geom..:

0.0 2.0 4 geom.. at hat s .  ;; exponentially spaced

Gating at

Wrap at expressions in quotations for conditional timing:

{ 0 0.25 0.5 0.75 at } 2 every    ;; 16th-note hats every other bar
hat s .

{ 0 0.5 at } 0.5 chance           ;; 50% chance of double-hit
kick s .

When the quotation doesn't execute, no deltas are set -- you get the default single emit at beat start.

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