shuffle :: Int -> Pattern a -> Pattern a
shuffle takes a number and a pattern as input, divides the pattern into the given number of parts, and returns a new pattern as a random permutation of the parts, picking one of each per cycle. This could also be called "sampling without replacement". For example:
d1 $ sound $ shuffle 3 "bd sn hh"
... will sometimes play
"sn bd hh" or
"hh sn bd", but will never play
"bd sn bd" or
"hh hh hh", because that isn't a permutation of the three parts.
See also: scramble