trigger

Type: trigger :: Show a => a -> Pattern b -> Pattern b

The trigger function causes the pattern passed to it to be 'reset' every time its evaluated. In the following example, the gain envelope resets each time the pattern is run:

d1 $ sound "bd*2 cp:4(5,8,<0 2>)"
  # gain (trigger 1 $ slow 2 envL)

Or similarly with a dj filteR:

d1 $ sound "bd*2 cp:4(5,8,<0 2>)"
  # djf (trigger 1 $ range 0.1 0.9 $ slow 2 envL)

The first parameter is the id of the pattern that does the triggering. In the above examples, it's 1, so in this case d1 is triggering itself.

In this example, running the d2 pattern resets the envelope in the d1 pattern:

d1 $ sound "bd*2 cp:4(5,8,<0 2>)"
  # djf (trigger 2 $ range 0.1 0.9 $ slow 2 envL)

d2 $ sound "~ arpy*2"

Note that if you manipulate time after a trigger, e.g. with fast or slow, then you will also be manipulating the trigger point and the results will probably not be what you intended. For example the fast in the following will move the trigger point into the past, so the envelope is immediately opened fully:

d1 $ fast 2 $ sound "bd*2 cp:4(5,8,<0 2>)"
  # djf (trigger 1 $ range 0.1 0.9 $ slow 2 envL)

The above can be fixed by only applying fast to the part of the pattern you want to speed up:

d1 $ (fast 2 $ sound "bd*2 cp:4(5,8,<0 2>)")
  # djf (trigger 1 $ range 0.1 0.9 $ slow 2 envL)