Week 8, Lesson 3 - fitting values to patterns with 'fit'

Ok after some delay, I'm back to finish off week 8 finally!

Here's a look at the fit function. I'd be happy to see your thoughts and questions about this one!

Here's the worksheet:

-- Lets fit things from a list, into a pattern!

-- Here's the 'type signature', what's it telling us?
fit :: Int -> [a] -> Pattern Int -> Pattern a

-- 'fit' takes a whole number, a list of things, a pattern of whole numbers,
-- and then gives back a pattern of things.

-- Int - a 'step size' - how far to advance through the list each cycle
-- [a] - a list - the things you want to put in the tattern
-- Pattern Int - a pattern of numbers referring to things in the list
-- Pattern a - the result! 'Pattern a' means it can work with any kind of
-- pattern

-- Let's start simple, with a step size of 0

d1 $ n (fit 0 [9,10,11,12,13,14] "0 1 2 3") # s "alphabet"

-- That's just cycling through four letters of the alphabet (j,k,l,m).
-- We have six numbers in our list, but we're only using the first four
-- (from 0 to 3).

-- Let's use all six, and add a bit more structure:
d1 $ n (fit 0 [9,10,11,12,13,14] "[0 3] [1 2] 4 [~ 5]") # s "alphabet"

-- Note that if you go past the end of the list, you go back to the start again.
-- So '0' and '6' end up pointing at the first of the six numbers, which is '9'
-- (which gives us 'j')
d1 $ n (fit 0 [9,10,11,12,13,14] "0 6") # s "alphabet"

-- Ok what if we start playing with that 'step size'?
d1 $ n (fit 1 [9,10,11,12,13,14] "0 1 2 ~") # s "alphabet"

-- It starts getting confusing, but you should be able to hear that each cycle,
-- the pattern moves through the list by one step, until it gets back to the
-- start again. So if it starts from 'j', 'k', 'l', the next cycle it'll shift
-- along by one and give 'k', 'l', 'm', and so on, until it starts wrapping
-- around to the start again.

-- This can be nice for generating melodies. The rhythm stays the same, but
-- the notes evolve, moving through the pattern
d1 $ note (fit 2 [0,2,7,5,12] "0 ~ 1 [2 3]") # sound "supermandolin"
  # legato 2 # gain 1.3

d2 $ n "0 ~ 2 [3*2 4*2]" # sound "cpu" # speed 2
6 Likes

Thank you, really interesting!

Maybe a tangential question: say I want to generate an array of n random integers within a range, how do I do it in haskell?

In Haskell you can do

import System.Random
let pureGen = mkStdGen 137

take 5 $ randomRs(0,1.0) $ pureGen
take 100 $ randomRs(2,4) $ pureGen

unfortunately it is not that simple in Tidal Cycles since for obscure reasons it does not easily accept to import System.Random

I finally suceeded by adding :set -package Random at the top of my BootTidal.hs as explained in https://club.tidalcycles.org/t/week-4-lesson-2-random-marathon-rand-irand-mininotation-randomness-scramble-shuffle-choose-more/685/36?u=abertier64

2 Likes

Thank you!

1 Like

Great function!

1 Like

Great little function and explanation!

How would one go about making it select sample banks as mentioned in the video?