every turns a static pattern into an evolving one by transforming it on every Nth cycle

every n f p applies transformation f to pattern p on every nth cycle and leaves it unchanged otherwise, so a single simple sequence develops over time on its own without preparing separate sections. The transform can be any pattern function (rev, fast, slow, hurry) or an effect written as a section (# vowel "a o", # squiz 5). Because the function is passed as a value (a partially applied function or a section), it must be parenthesized when it takes an argument — every 3 (fast 2) p, not every 3 $ fast 2 $ .... Multiple every calls can be chained on different periods to layer cheap variation; when their periods coincide (e.g. cycle 12 for periods 3 and 4) both transforms apply that cycle. This is a core live-coding idiom: long-form development and tension from minimal material.

Examples

d1 $ every 4 (fast 2) $ sound "arpy arpy:1 arpy:2 arpy:3"
d1 $ every 4 (# vowel "a o") $ sound "arpy arpy:1 arpy:2 arpy:3"
d1 $ every 3 rev $ every 4 (fast 2) $ sound "arpy arpy:1 arpy:2 arpy:3"
d1 $ every 4 rev $ every 2 (hurry 2) $ every 3 (# squiz 5) $ sound "bd sd ~ cp"

Assessment

Write a drum pattern that reverses every 4 cycles and doubles speed every 3 cycles; describe what happens on cycle 12 when both conditions coincide. Explain why every 3 $ fast 2 $ sound "bd" does not work.