strudel/repl/src/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'.m.tone(kick).bypass('<0@7 1>/8'.m),
    '~ <x!7 [x@3 x]>'.m.tone(snare).bypass('<0@7 1>/4'.m),
    '[~ c4]*2'.m.tone(hihat)
  );
  
  const thru = (x) => x.transpose('<0 1>/8'.m).transpose(-1);
  const synths = stack(
    '<eb4 d4 c4 b3>/2'.m.scale(timeCat([3,'C minor'],[1,'C melodic minor']).slow(8)).groove('[~ x]*2'.m)
    .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'.m),
    '<C2 Bb1 Ab1 [G1 [G2 G1]]>/2'.m.groove('[x [~ x] <[~ [~ x]]!3 [x x]>@2]/2'.m.fast(2)).edit(thru).tone(bass),
    '<Cm7 Bb7 Fm7 G7b13>/2'.m.groove('~ [x@0.1 ~]'.m.fast(2)).voicings().edit(thru).every(2, early(1/8)).tone(keys).bypass('<0@7 1>/8'.m.early(1/4))
  )
  return stack(
    drums.fast(2), 
    synths
  ).slow(2);
}`}
  height={400}
/>

[Open this track in the REPL](https://strudel.tidalcycles.org/#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%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\``}
  height={600}
/>

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:

- Tie symbols "\_"
- Euclidean algorithm "c3(3,2,1)"
- 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)
)`}
  height={200}
/>

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, pure(b4).late(0.5))`} />

Note that we have to wrap b4 in **pure** to be able to call a the pattern modifier **early**.

There is the shorthand **p** for this:

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

### late(cycles)

Like early, but in the other direction:

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

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

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

TODO: should the function really run the first cycle?

### Functions not documented yet

- add
- sub
- sub
- mul
- div
- union
- every
- when
- off
- jux
- append
- superimpose
- internal Pattern functions?
- groove, TODO move to core from https://github.com/tidalcycles/strudel/blob/main/repl/src/groove.ts

## Tone API

TODO, see https://github.com/tidalcycles/strudel/blob/main/repl/src/tone.ts

## Tonal API

TODO, see

- https://github.com/tidalcycles/strudel/blob/main/repl/src/tonal.ts
- https://github.com/tidalcycles/strudel/blob/main/repl/src/voicings.ts

## MIDI API

TODO, see https://github.com/tidalcycles/strudel/blob/main/repl/src/midi.ts

# 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/)