# Pattern structure with \`euclid\` function **URL:** \ **Category:** TidalCycles\ **Tags:** questions\ **Created:** [28 September 2020 19:59 UTC](https://uzu.lurk.org/t/pattern-structure-with-euclid-function/2221 "2020-09-28T19:59:45Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![tgirod](https://uzu.lurk.org/letter_avatar_proxy/v4/letter/t/35a633/32.png) [@tgirod](https://uzu.lurk.org/u/tgirod)\ **Post date:** [28 September 2020 19:59 UTC](https://uzu.lurk.org/t/pattern-structure-with-euclid-function/2221/1 "2020-09-28T19:59:45Z")
Hi, new to Tidal, played a bit with haskell ages ago, got a ton of questions! I'd like to reproduce the following pattern with the `euclid` function instead of the parenthesis notation: ```haskell d1 $ sound "bass(3,8)" # note (run 8)` ``` Here, the structure is taken from `bass(3,8)`, and the note will be selected based on the alignment between the two patterns. Now, if I write: ```haskell d1 $ euclid 3 8 $ sound "bass" # note (run 8) ``` Here, the note pattern gets restarted on each beat, effectively rendering it useless. But if i write: ```haskell d1 $ (# note (run 8)) $ euclid 3 8 $ sound "bass" ``` Here it works, but I'm unsure of the reason. I think I don't get how the "pattern structure comes from the left" rule is applied in this case. Can anyone explain? ---
**Author:** ![cleary](https://uzu.lurk.org/user_avatar/uzu.lurk.org/cleary/32/177_2.png) [@cleary](https://uzu.lurk.org/u/cleary)\ **Post date:** [29 September 2020 03:28 UTC](https://uzu.lurk.org/t/pattern-structure-with-euclid-function/2221/2 "2020-09-29T03:28:30Z")
I'll have a go! > Now, if I write: > `d1 $ euclid 3 8 $ sound "bass" # note (run 8)` > Here, the note pattern gets restarted on each beat, effectively rendering it useless. I think the trick to highlight the issue, is to take the `euclid` function away, ie: ```haskell d1 $ sound "bass" # note (run 8) ``` Will only play the first note of `run` on each cycle, since the pattern is coming from `sound "bass"` (played once each cycle) effectively rendering the `# note (run 8)` useless in this context as well. Then applying the `euclid 3 8` pattern, only patterns the single note sound. > But if i write: > `d1 $ (# note (run 8)) $ euclid 3 8 $ sound "bass"` > Here it works, but I'm unsure of the reason. I think I don't get how the "pattern structure comes from the left" rule is applied in this case. You've got a pattern of notes in this case - which starts as: `0 1 2 3 4 5 6 7 8` Is changed by `euclid` function to something like: `0 3 6` and then that pattern (and note value/pitch) is applied to the `sound "bass"` I'm unsure if that's going to clear anything up - but I hope it helps in some way 🙂 ---
**Author:** ![tgirod](https://uzu.lurk.org/letter_avatar_proxy/v4/letter/t/35a633/32.png) [@tgirod](https://uzu.lurk.org/u/tgirod)\ **Post date:** [29 September 2020 09:00 UTC](https://uzu.lurk.org/t/pattern-structure-with-euclid-function/2221/3 "2020-09-29T09:00:38Z")
Thanks, your answer helps a lot! So if I understand correctly, flipping `sound "bass"` and `note (run 8)` should make it work. ```haskell d1 $ euclid 3 8 $ note (run 8) # sound "bass" -- should be the same as d2 $ sound "bass(3,8)" # note (run 8) -- this ``` But it is not. Here, on each beat of the euclidean rythm, the whole `note (run 8)` is squeezed inside 1/8th of a cycle. 😕 I thought it would go like this: ```haskell 1 | 0 | 0 | 1 | 0 | 0 | 1 | 0 -- euclid 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 -- note (run 8) ----------------------------- 0 | x | x | 3 | x | x | 6 | x ``` ---
**Author:** ![gamar3is](https://uzu.lurk.org/user_avatar/uzu.lurk.org/gamar3is/32/3020_2.png) [@gamar3is](https://uzu.lurk.org/u/gamar3is)\ **Post date:** [29 September 2020 11:36 UTC](https://uzu.lurk.org/t/pattern-structure-with-euclid-function/2221/4 "2020-09-29T11:36:38Z")
I can't test at the moment, but have a suggestion since I've been playing with this kind of note masking recently -- `struct` might help to achieve what you outline on your diagram: ```haskell d1 $ struct "t(3,8)" $ note (run 8) # sound "bass" ``` The `t` in `struct` stands for `true`; with this you can "pick" notes from a pattern using an euclidean rhythm, or any other sequence. Does this help? ---
**Author:** ![tgirod](https://uzu.lurk.org/letter_avatar_proxy/v4/letter/t/35a633/32.png) [@tgirod](https://uzu.lurk.org/u/tgirod)\ **Post date:** [29 September 2020 11:55 UTC](https://uzu.lurk.org/t/pattern-structure-with-euclid-function/2221/5 "2020-09-29T11:55:45Z")
That's interesting, I didn't know about `struct`! My goal is to define the rythm structure with a function, as euclid's parameters come from an external controler - so your suggestion won't do it for me. But it led me to this: ```haskell d1 $ struct (euclidOffBool 3 8 0 "t") $ note (run 8) # sound "bass" ``` Well, `euclidOffBool` is not documented so it looks like it's working but I'm not absolutely sure it will always be the case. ---
**Author:** ![tgirod](https://uzu.lurk.org/letter_avatar_proxy/v4/letter/t/35a633/32.png) [@tgirod](https://uzu.lurk.org/u/tgirod)\ **Post date:** [29 September 2020 12:39 UTC](https://uzu.lurk.org/t/pattern-structure-with-euclid-function/2221/6 "2020-09-29T12:39:41Z")
Alright, got an answer from the toplap chat - putting it there for the sake of completeness. ```haskell d1 $ (euclid 3 8 $ sound "bass") # note (run 8) ``` by adding the parentheses, I'm applying `euclid 3 8` to `sound "bass"` only, and only then do I combine it with `note (run 8)`. So simple ...