strudel-docker/packages/tutorial/tutorial.mdx

import MiniRepl from './MiniRepl';

# What is Strudel?

With Strudel, you can expressively write dynamic music pieces.
It aims to be [Tidal Cycles](https://tidalcycles.org/) for JavaScript (started by the same author).

You don't need to know JavaScript or Tidal Cycles to make music with Strudel.

This interactive tutorial will guide you through the basics of Strudel.

The best place to actually make music with Strudel is the [Strudel REPL](https://strudel.tidalcycles.org/).

## Show me a Demo

To get a taste of what Strudel can do, check out this track:

<MiniRepl tune={`const delay = new FeedbackDelay(1/8, .4).chain(vol(0.5), out());
const kick = new MembraneSynth().chain(vol(.8), out());
const snare = new NoiseSynth().chain(vol(.8), out());
const hihat = new MetalSynth().set(adsr(0, .08, 0, .1)).chain(vol(.3).connect(delay),out());
const bass = new Synth().set({ ...osc('sawtooth'), ...adsr(0, .1, .4) }).chain(lowpass(900), vol(.5), out());
const keys = new PolySynth().set({ ...osc('sawtooth'), ...adsr(0, .5, .2, .7) }).chain(lowpass(1200), vol(.5), out());
const drums = stack(
"c1*2".tone(kick).bypass("<0@7 1>/8"),
"~ <x!7 [x@3 x]>".tone(snare).bypass("<0@7 1>/4"),
"[~ c4]*2".tone(hihat)
);
const thru = (x) => x.transpose("<0 1>/8").transpose(-1);
const synths = stack(
"<eb4 d4 c4 b3>/2".scale(timeCat([3,'C minor'],[1,'C melodic minor']).slow(8)).struct("[~ x]\*2")
.edit(
scaleTranspose(0).early(0),
scaleTranspose(2).early(1/8),
scaleTranspose(7).early(1/4),
scaleTranspose(8).early(3/8)
).edit(thru).tone(keys).bypass("<1 0>/16"),
"<C2 Bb1 Ab1 [G1 [G2 G1]]>/2".struct("[x [~ x] <[~ [~ x]]!3 [x x]>@2]/2".fast(2)).edit(thru).tone(bass),
"<Cm7 Bb7 Fm7 G7b13>/2".struct("~ [x@0.1 ~]".fast(2)).voicings().edit(thru).every(2, early(1/8)).tone(keys).bypass("<0@7 1>/8".early(1/4))
)
stack(
drums.fast(2),
synths
).slow(2);
`}
/>

[Open this track in the REPL](https://strudel.tidalcycles.org/#KCkgPT4gewogIGNvbnN0IGRlbGF5ID0gbmV3IEZlZWRiYWNrRGVsYXkoMS84LCAuNCkuY2hhaW4odm9sKDAuNSksIG91dCk7CiAgY29uc3Qga2ljayA9IG5ldyBNZW1icmFuZVN5bnRoKCkuY2hhaW4odm9sKC44KSwgb3V0KTsKICBjb25zdCBzbmFyZSA9IG5ldyBOb2lzZVN5bnRoKCkuY2hhaW4odm9sKC44KSwgb3V0KTsKICBjb25zdCBoaWhhdCA9IG5ldyBNZXRhbFN5bnRoKCkuc2V0KGFkc3IoMCwgLjA4LCAwLCAuMSkpLmNoYWluKHZvbCguMykuY29ubmVjdChkZWxheSksb3V0KTsKICBjb25zdCBiYXNzID0gbmV3IFN5bnRoKCkuc2V0KHsgLi4ub3NjKCdzYXd0b290aCcpLCAuLi5hZHNyKDAsIC4xLCAuNCkgfSkuY2hhaW4obG93cGFzcyg5MDApLCB2b2woLjUpLCBvdXQpOwogIGNvbnN0IGtleXMgPSBuZXcgUG9seVN5bnRoKCkuc2V0KHsgLi4ub3NjKCdzYXd0b290aCcpLCAuLi5hZHNyKDAsIC41LCAuMiwgLjcpIH0pLmNoYWluKGxvd3Bhc3MoMTIwMCksIHZvbCguNSksIG91dCk7CiAgCiAgY29uc3QgZHJ1bXMgPSBzdGFjaygKICAgICdjMSoyJy5tLnRvbmUoa2ljaykuYnlwYXNzKCc8MEA3IDE%2BLzgnLm0pLAogICAgJ34gPHghNyBbeEAzIHhdPicubS50b25lKHNuYXJlKS5ieXBhc3MoJzwwQDcgMT4vNCcubSksCiAgICAnW34gYzRdKjInLm0udG9uZShoaWhhdCkKICApOwogIAogIGNvbnN0IHRocnUgPSAoeCkgPT4geC50cmFuc3Bvc2UoJzwwIDE%2BLzgnLm0pLnRyYW5zcG9zZSgtMSk7CiAgY29uc3Qgc3ludGhzID0gc3RhY2soCiAgICAnPGViNCBkNCBjNCBiMz4vMicubS5zY2FsZSh0aW1lQ2F0KFszLCdDIG1pbm9yJ10sWzEsJ0MgbWVsb2RpYyBtaW5vciddKS5zbG93KDgpKS5ncm9vdmUoJ1t%2BIHhdKjInLm0pCiAgICAuZWRpdCgKICAgICAgc2NhbGVUcmFuc3Bvc2UoMCkuZWFybHkoMCksCiAgICAgIHNjYWxlVHJhbnNwb3NlKDIpLmVhcmx5KDEvOCksCiAgICAgIHNjYWxlVHJhbnNwb3NlKDcpLmVhcmx5KDEvNCksCiAgICAgIHNjYWxlVHJhbnNwb3NlKDgpLmVhcmx5KDMvOCkKICAgICkuZWRpdCh0aHJ1KS50b25lKGtleXMpLmJ5cGFzcygnPDEgMD4vMTYnLm0pLAogICAgJzxDMiBCYjEgQWIxIFtHMSBbRzIgRzFdXT4vMicubS5ncm9vdmUoJ1t4IFt%2BIHhdIDxbfiBbfiB4XV0hMyBbeCB4XT5AMl0vMicubS5mYXN0KDIpKS5lZGl0KHRocnUpLnRvbmUoYmFzcyksCiAgICAnPENtNyBCYjcgRm03IEc3YjEzPi8yJy5tLmdyb292ZSgnfiBbeEAwLjEgfl0nLm0uZmFzdCgyKSkudm9pY2luZ3MoKS5lZGl0KHRocnUpLmV2ZXJ5KDIsIGVhcmx5KDEvOCkpLnRvbmUoa2V5cykuYnlwYXNzKCc8MEA3IDE%2BLzgnLm0uZWFybHkoMS80KSkKICApCiAgcmV0dXJuIHN0YWNrKAogICAgZHJ1bXMuZmFzdCgyKSwgCiAgICBzeW50aHMKICApLnNsb3coMik7Cn0%3D)

## Disclaimer

- This project is still in its experimental state. In the future, parts of it might change significantly.
- This tutorial is far from complete.

<br />

# Mini Notation

Similar to Tidal Cycles, Strudel has an embedded mini language that is designed to write rhythmic patterns in a short manner.
Before diving deeper into the details, here is a flavor of how the mini language looks like:

<MiniRepl
  tune={`\`[
  [
    [e5 [b4 c5] d5 [c5 b4]]
    [a4 [a4 c5] e5 [d5 c5]]
    [b4 [~ c5] d5 e5]
    [c5 a4 a4 ~]
    [[~ d5] [~ f5] a5 [g5 f5]]
    [e5 [~ c5] e5 [d5 c5]]
    [b4 [b4 c5] d5 e5]
    [c5 a4 a4 ~]
  ],[
    [[e2 e3]*4]
    [[a2 a3]*4]
    [[g#2 g#3]*2 [e2 e3]*2]
    [a2 a3 a2 a3 a2 a3 b1 c2]
    [[d2 d3]*4]
    [[c2 c3]*4]
    [[b1 b2]*2 [e2 e3]*2]
    [[a1 a2]*4]
  ]
]/16\``}
/>

The snippet above is enclosed in backticks (`), which allows you to write multi-line strings.
You can also use double quotes (") for single line mini notation.

## Notes

Notes are notated with the note letter, followed by the octave number. You can notate flats with `b` and sharps with `#`.

<MiniRepl tune={`"e5"`} />

Here, the same note is played over and over again, once a second. This one second is the default length of one so called "cycle".

By the way, you can edit the contents of the player, and press "update" to hear your change!
You can also press "play" on the next player without needing to stop the last one.

## Sequences

We can play more notes by seperating them with spaces:

<MiniRepl tune={`"e5 b4 d5 c5"`} />

Here, those four notes are squashed into one cycle, so each note is a quarter second long.

## Division

We can slow the sequence down by enclosing it in brackets and dividing it by a number:

<MiniRepl tune={`"[e5 b4 d5 c5]/2"`} />

The division by two means that the sequence will be played over the course of two cycles.
You can also use decimal numbers for any tempo you like.

## Angle Brackets

Using angle brackets, we can define the sequence length based on the number of children:

<MiniRepl tune={`"<e5 b4 d5 c5>"`} />

The above snippet is the same as:

<MiniRepl tune={`"[e5 b4 d5 c5]/4"`} />

The advantage of the angle brackets, is that we can add more children without needing to change the number at the end.

## Multiplication

Contrary to division, a sequence can be sped up by multiplying it by a number:

<MiniRepl tune={`"[e5 b4 d5 c5]*2"`} />

The multiplication by 2 here means that the sequence will play twice a cycle.

## Bracket Nesting

To create more interesting rhythms, you can nest sequences with brackets, like this:

<MiniRepl tune={`"e5 [b4 c5] d5 [c5 b4]"`} />

## Rests

The "~" represents a rest:

<MiniRepl tune={`"[b4 [~ c5] d5 e5]"`} />

## Parallel

Using commas, we can play chords:

<MiniRepl tune={`"g3,b3,e4"`} />

To play multiple chords in a sequence, we have to wrap them in brackets:

<MiniRepl tune={`"<[g3,b3,e4] [a3,c3,e4] [b3,d3,f#4] [b3,e4,g4]>"`} />

## Elongation

With the "@" symbol, we can specify temporal "weight" of a sequence child:

<MiniRepl tune={`"<[g3,b3,e4]@2 [a3,c3,e4] [b3,d3,f#4]>"`} />

Here, the first chord has a weight of 2, making it twice the length of the other chords. The default weight is 1.

## Replication

Using "!" we can repeat without speeding up:

<MiniRepl tune={`"<[g3,b3,e4]!2 [a3,c3,e4] [b3,d3,f#4]>"`} />

In essence, the `x!n` is like a shortcut for `[x*n]@n`.

## Mini Notation TODO

Compared to [tidal mini notation](https://tidalcycles.org/docs/patternlib/tutorials/mini_notation/), the following mini notation features are missing from Strudel:

- [x] Euclidean algorithm "c3(3,2,1)" TODO: document
- [ ] Tie symbols "\_"
- [ ] feet marking "."
- [ ] random choice "|"
- [ ] Random removal "?"
- [ ] Polymetric sequences "{ ... }"
- [ ] Fixed steps using "%"

<br />

# Core API

While the mini notation is powerful on its own, there is much more to discover.
Internally, the mini notation will expand to use the actual functional JavaScript API.

## Notes

Notes are automatically available as variables:

<MiniRepl tune={`e4`} />

An important difference to the mini notation:
For sharp notes, the letter "s" is used instead of "#", because JavaScript does not support "#" in a variable name.

The above is the same as:

<MiniRepl tune={`"e4"`} />

Using strings, you can also use "#".

## Functions that create Patterns

The following functions will return a pattern. We will see later what that means.

## pure(value)

To create a pattern from a value, you can wrap the value in pure:

<MiniRepl tune={`pure('e4')`} />

Most of the time, you won't need that function as input values of pattern creating functions are purified by default.

### cat(...values)

The given items are con**cat**enated spread evenly over one cycle:

<MiniRepl tune={`cat(e5, b4, d5, c5)`} />

The function **fastcat** does the same as **cat**.

### sequence(...values)

Like **cat**, but allows nesting with arrays:

<MiniRepl tune={`sequence(e5, [b4, c5], d5, [c5, b4])`} />

### stack(...values)

The given items are played at the same time at the same length:

<MiniRepl tune={`stack(g3,b3,e4)`} />

### slowcat(...values)

Like cat, but each item has the length of one cycle:

<MiniRepl tune={`slowcat(e5, b4, d5, c5)`} />

<!-- ## slowcatPrime ? -->

### Nesting functions

You can nest functions inside one another:

<MiniRepl
  tune={`slowcat(
  stack(g3,b3,e4),
  stack(a3,c3,e4),
  stack(b3,d3,fs4),
  stack(b3,e4,g4)
)`}
/>

The above is equivalent to

<MiniRepl tune={`"<[g3,b3,e4] [a3,c3,e4] [b3,d3,f#4] [b3,e4,g4]>"`} />

### timeCat(...[weight,value])

Like with "@" in mini notation, we can specify weights to the items in a sequence:

<MiniRepl tune={`timeCat([3,e3],[1, g3])`} />

<!-- ## polymeter

how to use?

<MiniRepl tune={`polymeter(3, e3, g3, b3)`} /> -->

### polyrhythm(...[...values])

Plays the given items at the same time, within the same length:

<MiniRepl tune={`polyrhythm([e3, g3], [e4, g4, b4])`} />

We can write the same with **stack** and **cat**:

<MiniRepl tune={`stack(cat(e3, g3), cat(e4, g4, b4))`} />

You can also use the shorthand **pr** instead of **polyrhythm**.

## Pattern modifier functions

The following functions modify a pattern.

### slow(factor)

Like "/" in mini notation, **slow** will slow down a pattern over the given number of cycles:

<MiniRepl tune={`cat(e5, b4, d5, c5).slow(2)`} />

The same in mini notation:

<MiniRepl tune={`"[e5 b4 d5 c5]/2"`} />

### fast(factor)

Like "\*" in mini notation, **fast** will play a pattern times the given number in one cycle:

<MiniRepl tune={`cat(e5, b4, d5, c5).fast(2)`} />

### early(cycles)

With early, you can nudge a pattern to start earlier in time:

<MiniRepl tune={`cat(e5, b4.early(0.5))`} />

### late(cycles)

Like early, but in the other direction:

<MiniRepl tune={`cat(e5, b4.late(0.5))`} />

<!-- TODO: shouldn't it sound different? -->

### rev()

Will reverse the pattern:

<MiniRepl tune={`cat(c3,d3,e3,f3).rev()`} />

### every(n, func)

Will apply the given function every n cycles:

<MiniRepl tune={`cat(e5, pure(b4).every(4, late(0.5)))`} />

<!-- TODO: should be able to do b4.every => like already possible with fast slow etc.. -->

Note that late is called directly. This is a shortcut for:

<MiniRepl tune={`cat(e5, pure(b4).every(4, x => x.late(0.5)))`} />

<!-- TODO: should the function really run the first cycle? -->

### add(n)

Adds the given number to each item in the pattern:

<MiniRepl tune={`"0 2 4".add("<0 3 4 0>").scale('C major')`} />

Here, the triad `0, 2, 4` is shifted by different amounts. Without add, the equivalent would be:

<MiniRepl tune={`"<[0 2 4] [3 5 7] [4 6 8] [0 2 4]>".scale('C major')`} />

You can also use add with notes:

<MiniRepl tune={`"c3 e3 g3".add("<0 5 7 0>")`} />

Behind the scenes, the notes are converted to midi numbers as soon before add is applied, which is equivalent to:

<MiniRepl tune={`"48 52 55".add("<0 5 7 0>")`} />

### sub(n)

Like add, but the given numbers are subtracted:

<MiniRepl tune={`"0 2 4".sub("<0 1 2 3>").scale('C4 minor')`} />

See add for more information.

### mul(n)

Multiplies each number by the given factor:

<MiniRepl tune={`"0,1,2".mul("<2 3 4 3>").scale('C4 minor')`} />

... is equivalent to:

<MiniRepl tune={`"<[0,2,4] [0,3,6] [0,4,8] [0,3,6]>".scale('C4 minor')`} />

This function is really useful in combination with signals:

<MiniRepl tune={`sine.struct("x*16").mul(7).round().scale('C major')`} />

Here, we sample a sine wave 16 times, and multiply each sample by 7. This way, we let values oscillate between 0 and 7.

### div(n)

Like mul, but dividing by the given number.

### round()

Rounds all values to the nearest integer:

<MiniRepl tune={`"0.5 1.5 2.5".round().scale('C major')`} />

### struct(binary_pat)

Applies the given structure to the pattern:

<MiniRepl tune={`"c3,eb3,g3".struct("x ~ x ~ ~ x ~ x ~ ~ ~ x ~ x ~ ~").slow(4)`} />

This is also useful to sample signals:

<MiniRepl
  tune={`sine.struct("x ~ x ~ ~ x ~ x ~ ~ ~ x ~ x ~ ~").mul(7).round()
.scale('C minor').slow(4)`}
/>

### when(binary_pat, func)

Applies the given function whenever the given pattern is in a true state.

<MiniRepl tune={`"c3 eb3 g3".when("<0 1>/2", sub(5))`} />

### superimpose(...func)

Superimposes the result of the given function(s) on top of the original pattern:

<MiniRepl tune={`"<c3 eb3 g3>".scale('C minor').superimpose(scaleTranspose("2,4"))`} />

### layer(...func)

Layers the result of the given function(s) on top of each other. Like superimpose, but the original pattern is not part of the result.

<MiniRepl tune={`"<c3 eb3 g3>".scale('C minor').layer(scaleTranspose("0,2,4"))`} />

### apply(func)

Like layer, but with a single function:

<MiniRepl tune={`"<c3 eb3 g3>".scale('C minor').apply(scaleTranspose("0,2,4"))`} />

### off(time, func)

Applies the given function by the given time offset:

<MiniRepl tune={`"c3 eb3 g3".off(1/8, add(7))`} />

### append(pat)

Appends the given pattern after the current pattern:

<MiniRepl tune={`"c4,eb4,g4".append("c4,f4,ab4")`} />

### stack(pat)

Stacks the given pattern to the current pattern:

<MiniRepl tune={`"c4,eb4,g4".stack("bb4,d5")`} />

## Tone API

To make the sounds more interesting, we can use Tone.js instruments ands effects.

[Show Source on Github](https://github.com/tidalcycles/strudel/blob/main/repl/src/tone.ts)

<MiniRepl
  tune={`stack(
    "[c5 c5 bb4 c5] [~ g4 ~ g4] [c5 f5 e5 c5] ~"
      .tone(synth(adsr(0,.1,0,0)).chain(out())),
    "[c2 c3]*8"
      .tone(synth({
        ...osc('sawtooth'),
        ...adsr(0,.1,0.4,0)
      }).chain(lowpass(300), out()))
  ).slow(4)`}
/>

### tone(instrument)

To change the instrument of a pattern, you can pass any [Tone.js Source](https://tonejs.github.io/docs/14.7.77/index.html) to .tone:

<MiniRepl
  tune={`"[c4 c4 bb3 c4] [~ g3 ~ g3] [c4 f4 e4 c4] ~".slow(4)
.tone(new FMSynth().toDestination())`}
/>

While this works, it is a little bit verbose. To simplify things, all Tone Synths have a shortcut:

```js
const amsynth = (options) => new AMSynth(options);
const duosynth = (options) => new DuoSynth(options);
const fmsynth = (options) => new FMSynth(options);
const membrane = (options) => new MembraneSynth(options);
const metal = (options) => new MetalSynth(options);
const monosynth = (options) => new MonoSynth(options);
const noise = (options) => new NoiseSynth(options);
const pluck = (options) => new PluckSynth(options);
const polysynth = (options) => new PolySynth(options);
const synth = (options) => new Synth(options);
const sampler = (options, baseUrl?) => new Sampler(options); // promisified, see below
const players = (options, baseUrl?) => new Sampler(options); // promisified, see below
```

### sampler

With sampler, you can create tonal instruments from samples:

<MiniRepl
  tune={`sampler({
  C5: 'https://freesound.org/data/previews/536/536549_11935698-lq.mp3'
}).then(kalimba => 
  saw.struct("x*8").mul(16).round()
  .legato(4).scale('D dorian').slow(2)
  .tone(kalimba.toDestination())
)`}
/>

The sampler function promisifies [Tone.js Sampler](https://tonejs.github.io/docs/14.7.77/Sampler).

Note that this function currently only works with this promise notation, but in the future,
it will be possible to use async instruments in a synchronous fashion.

### players

With players, you can create sound banks:

<MiniRepl
  tune={`players({
    bd: 'samples/tidal/bd/BT0A0D0.wav',
    sn: 'samples/tidal/sn/ST0T0S3.wav',
    hh: 'samples/tidal/hh/000_hh3closedhh.wav'
  }, 'https://loophole-letters.vercel.app/')
  .then(drums=>
  "bd hh sn hh".tone(drums.toDestination())
)
  `}
/>

The sampler function promisifies [Tone.js Players](https://tonejs.github.io/docs/14.7.77/Players).

Note that this function currently only works with this promise notation, but in the future,
it will be possible to use async instruments in a synchronous fashion.

### out

Shortcut for Tone.Destination. Intended to be used with Tone's .chain:

<MiniRepl
  tune={`"[c4 c4 bb3 c4] [~ g3 ~ g3] [c4 f4 e4 c4] ~".slow(4)
.tone(membrane().chain(out()))`}
/>

This alone is not really useful, so read on..

### vol(volume)

Helper that returns a Gain Node with the given volume. Intended to be used with Tone's .chain:

<MiniRepl
  tune={`"[c4 c4 bb3 c4] [~ g3 ~ g3] [c4 f4 e4 c4] ~".slow(4)
.tone(noise().chain(vol(0.5), out()))`}
/>

### osc(type)

Helper to set the waveform of a synth, monosynth or polysynth:

<MiniRepl
  tune={`"[c4 c4 bb3 c4] [~ g3 ~ g3] [c4 f4 e4 c4] ~".slow(4)
.tone(synth(osc('sawtooth4')).chain(out()))`}
/>

The base types are `sine`, `square`, `sawtooth`, `triangle`. You can also append a number between 1 and 32 to reduce the harmonic partials.

### lowpass(cutoff)

Helper that returns a Filter Node of type lowpass with the given cutoff. Intended to be used with Tone's .chain:

<MiniRepl
  tune={`"[c4 c4 bb3 c4] [~ g3 ~ g3] [c4 f4 e4 c4] ~".slow(4)
.tone(synth(osc('sawtooth')).chain(lowpass(800), out()))`}
/>

### highpass(cutoff)

Helper that returns a Filter Node of type highpass with the given cutoff. Intended to be used with Tone's .chain:

<MiniRepl
  tune={`"[c4 c4 bb3 c4] [~ g3 ~ g3] [c4 f4 e4 c4] ~".slow(4)
.tone(synth(osc('sawtooth')).chain(highpass(2000), out()))`}
/>

### adsr(attack, decay?, sustain?, release?)

Helper to set the envelope of a Tone.js instrument. Intended to be used with Tone's .set:

<MiniRepl
  tune={`"[c4 c4 bb3 c4] [~ g3 ~ g3] [c4 f4 e4 c4] ~".slow(4)
.tone(synth(adsr(0,.1,0,0)).chain(out()))`}
/>

### Experimental: Patternification

While the above methods work for static sounds, there is also the option to patternify tone methods.
This is currently experimental, because the performance is not stable, and audio glitches will appear after some time.
It would be great to get this to work without glitches though, because it is fun!

#### synth(type)

With .synth, you can create a synth with a variable wave type:

<MiniRepl
  tune={`"[c4 c4 bb3 c4] [~ g3 ~ g3] [c4 f4 e4 c4] ~"
.synth("<sawtooth8 square8>").slow(4)`}
/>

#### adsr(attack, decay?, sustain?, release?)

Chainable Envelope helper:

<MiniRepl
  tune={`"[c5 c5 bb4 c5] [~ g4 ~ g4] [c5 f5 e5 c5] ~".slow(4)
  .synth('sawtooth16').adsr(0,.1,0,0)`}
/>

Due to having more than one argument, this method is not patternified.

#### filter(cuttoff)

Patternified filter:

<MiniRepl
  tune={`"[c4 c4 bb3 c4] [~ g3 ~ g3] [c4 f4 e4 c4] ~"
  .synth('sawtooth16').filter("[500 2000]*8").slow(4)`}
/>

#### gain(value)

Patternified gain:

<MiniRepl
  tune={`"[c4 c4 bb3 c4] [~ g3 ~ g3] [c4 f4 e4 c4] ~"
  .synth('sawtooth16').gain("[.2 .8]*8").slow(4)`}
/>

#### autofilter(value)

Patternified autofilter:

<MiniRepl
  tune={`"c2 c3"
  .synth('sawtooth16').autofilter("<1 4 8>"")`}
/>

## Tonal API

The Tonal API, uses [tonaljs](https://github.com/tonaljs/tonal) to provide helpers for musical operations.

### transpose(semitones)

Transposes all notes to the given number of semitones:

<MiniRepl tune={`"c2 c3".fast(2).transpose("<0 -2 5 3>".slow(2)).transpose(0)`} />

This method gets really exciting when we use it with a pattern as above.

Instead of numbers, scientific interval notation can be used as well:

<MiniRepl tune={`"c2 c3".fast(2).transpose("<1P -2M 4P 3m>".slow(2)).transpose(1)`} />

### scale(name)

Turns numbers into notes in the scale (zero indexed). Also sets scale for other scale operations, like scaleTranpose.

<MiniRepl
  tune={`"0 2 4 6 4 2"
.scale(slowcat('C2 major', 'C2 minor').slow(2))`}
/>

Note that the scale root is octaved here. You can also omit the octave, then index zero will default to octave 3.

All the available scale names can be found [here](https://github.com/tonaljs/tonal/blob/main/packages/scale-type/data.ts).

### scaleTranspose(steps)

Transposes notes inside the scale by the number of steps:

<MiniRepl
  tune={`"-8 [2,4,6]"
.scale('C4 bebop major')
.scaleTranspose("<0 -1 -2 -3 -4 -5 -6 -4>")`}
/>

### voicings(range?)

Turns chord symbols into voicings, using the smoothest voice leading possible:

<MiniRepl tune={`stack("<C^7 A7 Dm7 G7>".voicings(), "<C3 A2 D3 G2>")`} />

<!-- TODO: use voicing collection as first param + patternify. -->

### rootNotes(octave = 2)

Turns chord symbols into root notes of chords in given octave.

<MiniRepl tune={`"<C^7 A7b13 Dm7 G7>".rootNotes(3)`} />

Together with edit, struct and voicings, this can be used to create a basic backing track:

<MiniRepl
  tune={`"<C^7 A7b13 Dm7 G7>".edit(
  x => x.voicings(['d3','g4']).struct("~ x"),
  x => x.rootNotes(2).tone(synth(osc('sawtooth4')).chain(out()))
)`}
/>

<!-- TODO: use range instead of octave. -->
<!-- TODO: find out why composition does not work -->

## Microtonal API

TODO

## MIDI API

Strudel also supports midi via [webmidi](https://npmjs.com/package/webmidi).

### midi(outputName?)

Make sure to have a midi device connected or to use an IAC Driver.
If no outputName is given, it uses the first midi output it finds.

Midi is currently not supported by the mini repl used here, but you can [open the midi example in the repl](https://strudel.tidalcycles.org/#c3RhY2soIjxDXjcgQTcgRG03IEc3PiIubS52b2ljaW5ncygpLCAnPEMzIEEyIEQzIEcyPicubSkKICAubWlkaSgp).

In the REPL, you will se a log of the available MIDI devices.

<!--<MiniRepl
  tune={`stack("<C^7 A7 Dm7 G7>".voicings(), "<C3 A2 D3 G2>")
  .midi()`}
/>-->

# Contributing

Contributions of any sort are very welcome! You can contribute by editing [this file](https://github.com/tidalcycles/strudel/blob/main/repl/src/tutorial/tutorial.mdx).
All you need is a github account.

If you want to run the tutorial locally, you can clone the and run:

```sh
cd repl && npm i && npm run tutorial
```

If you want to contribute in another way, either

- [fork strudel repo on GitHub](https://github.com/tidalcycles/strudel)
- [Join the Discord Channel](https://discord.gg/remJ6gQA)
- [play with the Strudel REPL](https://strudel.tidalcycles.org/)