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Randomness

This page will present you all the functions that can be used to introduce some randomness in your musical patterns. Each function will be presented following the same model:

  • Type signature: how the function is declared on the Haskell side.
  • Description: verbal description of the function.
  • Examples: a small list of examples that you can copy/paste in your editor.

Pseudo-randomisation#

rand#

Type: rand :: Fractional a => Pattern a

rand is an oscillator that generates a pattern of (pseudo-)random, floating point numbers between 0.0 and 1.0. For example to randomly pan around the stereo field you can:

d1 $ sound "bd*8" # pan rand

Or to enjoy a randomised speed from 0.5 to 1.5, you can add 0.5 to it.

d1 $ sound "arpy*4" # speed (rand + 0.5)

irand#

Type: irand :: Num a => Int -> Pattern a

irand is similar to rand, but generates a continuous oscillator of (pseudo-)random integers between 0 to n-1 inclusive. Notably used to pick random samples from a folder.

d1 $ sound "amencutup*8" # n (irand 8)

Perlin noise#

perlin#

Type: perlin :: Pattern Double

perlin produces 1D Perlin (smooth) noise. It works like rand but smoothly moves between random values each cycle. For example, you can smoothly and randomly change speed:

d1 $ sound "bd*32" # speed (perlin + 0.5)

The perlin function produces a new random value to move to every cycle. If you want a new random value to be generated more or less frequently, you can use fast or slow, respectively:

d1 $ sound "bd*32" # speed (fast 4 $ perlin + 0.5)
d1 $ sound "bd*32" # speed (slow 4 $ perlin + 0.5)

perlinWith#

perlinWith allows you to specify a pattern as input to generate random values instead of using the default cycle count:

d1 $ s "arpy*32" # cutoff (perlinWith (saw * 4) * 2000)

perlin2#

perlin2 creates 2D noise by allowing you to specify a custom pattern as a second dimension (cycle number remains as the first dimension):

d1 $ s "bd*32" # speed (perlin2 (sine*4) + 1)

perlin2With#

perlin2With is the same as perlinWith except allows you to provide two functions for 2D noise:

d1
$ s "[arpy*32]"
# lpf (range 60 5000 $ perlin2With (cosine*2) (sine*2))
# lpq 0.3

The "sometimes" family#

sometimes#

Type: sometimes :: (Pattern a -> Pattern a) -> Pattern a -> Pattern a

sometimes is function, that applies another function to a pattern, around 50% of the time, at random. It takes two inputs, the function to be applied, and the pattern you are applying it to.

For example to distort half the events in a pattern:

d1 $ sometimes (# crush 2) $ n "0 1 [~ 2] 3" # sound "arpy"

sometimes has a number of variants, which apply the function with different likelihood:

function likelihood
always100%
almostAlways90%
often75%
sometimes50%
rarely25%
almostNever10%
never0%

sometimesBy#

If you want to be specific, you can use sometimesBy and a number, for example:

sometimesBy 0.93 (# speed 2)

to apply the speed control on average 93 times out of a hundred.

someCycles#

someCycles is similar to sometimes, but instead of applying the given function to random events, it applies it to random cycles. For example the following will either distort all of the events in a cycle, or none of them:

d1 $ someCycles (# crush 2) $ n "0 1 [~ 2] 3" # sound "arpy"

someCyclesBy#

As with sometimesBy, if you want to be specific, you can use someCyclesBy and a number. For example:

someCyclesBy 0.93 (# speed 2)

will apply the speed control on average 93 cycles out of a hundred.

Choosing randomly#

choose#

Type: choose :: [a] -> Pattern a

The choose function emits a stream of randomly choosen values from the given list, as a continuous pattern:

d1 $ sound "drum ~ drum drum" # n (choose [0,2,3])

As with all continuous patterns, you have to be careful to give them structure; in this case choose gives you an infinitely detailed stream of random choices.

chooseby#

Type: chooseBy :: Pattern Double -> [a] -> Pattern a

The chooseBy function is like choose but instead of selecting elements of the list randomly, it uses the given pattern to select elements.

chooseBy "0 0.25 0.5" ["a","b","c","d"]

will result in the pattern "a b c" .

wchoose#

Type: wchoose :: [(a, Double)] -> Pattern a

wchoose is similar to choose, but allows you to 'weight' the choices, so some are more likely to be chosen than others. The following is similar to the previous example, but the 2 is twice as likely to be chosen than the 0 or 3.

d1 $ sound "drum ~ drum drum" # n (wchoose [(0,0.25),(2,0.5),(3,0.25)])
caution

Prior to version 1.0.0 of Tidal, the weights had to add up to 1, but this is no longer the case.

wchooseby#

Type: wchooseBy :: Pattern Double -> [(a,Double)] -> Pattern a

The wchooseBy function is like wchoose but instead of selecting elements of the list randomly, it uses the given pattern to select elements.

cycleChoose#

Type: cycleChoose :: [a] -> Pattern a

Similar to choose, but only picks once per cycle:

d1 $ sound "drum ~ drum drum" # n (cycleChoose [0,2,3])
Last updated on by Renzo Torr-