stack layers a list of patterns to play simultaneously so one transformation can shape them all

stack takes a list of patterns and combines them into a new pattern by playing all of them at once, in a single d1 channel. This is the primary tool for building a full arrangement (drums, hats, melody) as one object. Its key advantage over separate connections is that any function or effect chain applied to the stack shapes every layer together: d1 $ every 4 (slow 2) $ stack [...] slows the whole arrangement every fourth cycle, and a trailing # speed "..." re-pitches all layers uniformly. Contrast with the serial concatenators (cat/fastcat), which play their list one pattern after another rather than simultaneously.

Examples

d1 $ every 4 (slow 2) $ stack [
  sound "bd bd*2",
  sound "hh*2 [sn cp] cp future*4",
  sound (samples "arpy*8" (run 16))
]

Assessment

Write a stacked three-layer pattern (kick, hats, melody) and apply a single every 4 (rev) so that all three layers reverse together every fourth cycle. Explain why stacking (not three separate d-channels) is needed here.