Working with groups of co-occuring events

Innards
2

Moved to Innards as it's a bit involved..

I'd generalise the type so it works with any number, as in Tidal notes aren't integers but floats.

inversion :: Num a => Int -> [a] -> [a]
inversion _ [] = []
inversion n xs = drop n xs ++ [ x + 12 | x <- take n xs ]

Then I'd get it to with with lists of Tidal events rather than values:

eventInversion :: Num a => Int -> [Event a] -> [Event a]
eventInversion _ [] = []
eventInversion n xs = drop n xs ++ (fmap (fmap (+12)) $ take n xs )

I used fmap to work in the values inside events, and for brevity used fmap on the list too instead of the list comprehension.

Then I made this function that allows you to group any co-occuring events and work on them together:

withFriends :: ([Event a] -> [Event b]) -> Pattern a -> Pattern b
withFriends f pat = withEvents munge pat
  where munge es = concatMap (f) (groupBy (\a b -> whole a == whole b) $ sortOn whole es)

Then bring it together:

invert :: Num b => Int -> Pattern b -> Pattern b
invert = withFriends . eventInversion

d1 $ n (invert 2 "c'maj e'min'4") $ sound "superpiano"
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