ifp :: (Int -> Bool) -> (Pattern a -> Pattern a) -> (Pattern a -> Pattern a) -> Pattern a -> Pattern a
ifp decides whether to apply one or another function depending on the result of a test function, which is passed the current cycle as a number. For example:
d1 $ ifp ((== 0).(flip mod 2)) (striate 4) (# coarse "24 48") $ sound "hh hc"
This will apply
striate 4 for every even cycle, and
# coarse "24 48" for every odd one.
Detail: The test function does not rely on anything tidal-specific, it uses plain Haskell functionality for operating on numbers. That is, it calculates the modulo of 2 of the current cycle which is either 0 (for even cycles) or 1. It then compares this value against 0 and returns the result, which is either True or False. This is what the first part of
ifp's type signature signifies (
Int -> Bool), a function that takes a whole number and returns either True or False.