# Week 7 Lesson 2 - Composing fuctions together with "."

Here's a quick video about the handy `.` operator:

``````-- Composing functions together

-- Lets say you wanted to both chop up, _and_ reverse this pattern,
-- every 3 cycles.
d1 \$ sound "bd [~ sd] bd sd" # squiz 2

-- You could do it like this:
d1 \$ every 3 (rev) \$ every 3 (chop 8) \$
sound "bd [~ sd] bd sd" # squiz 2

-- That works, but is a bit fiddly. This is where the `.` operator
-- comes in handy, by turning two functions into one:
d1 \$ every 3 (rev . chop 8) \$
sound "bd [~ sd] bd sd" # squiz 2

-- That works the same, but with less typing, good!

-- You can just think of the `.` as piping together two functions
-- into one.

-- But technically speaking:, the `.` will take the input, pass it into the
-- function on the right, take the output from _that_ function, pass
-- it to the function on the left, and finally return the return of
-- _that_ function.

-- You can keep piping in more functions, if you want:
d1 \$ every 3 (rev . chop 8 . fast 2) \$
sound "bd [~ sd] bd sd" # squiz 2

-- You can also add in effects:
d1 \$ every 3 ((# room 0.7) . rev . chop 8 . fast 2) \$
sound "bd [~ sd] bd sd" # squiz 2

Have fun!
``````
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I also found this comparison of Haskell's dot and dollar helpful https://stackoverflow.com/a/1290727/132208

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Time is strange <3