> ## Documentation Index > Fetch the complete documentation index at: https://pkhambat.mintlify.site/llms.txt > Use this file to discover all available pages before exploring further. # Overview > Cells, statements, types, names, blocks, lengths and scope. ## Cells A cell is a program. The interpreter evaluates its statements top to bottom, one per line, and each `play` renders one output. Nothing else makes sound. `//` starts a comment, and a line that starts with `|` continues the line above it, at a bar line. | Statement | Example | Allowed | | - | - | - | | Setting | `set tempo 90` | Top level only, outside every block. See [Settings](https://pkhambat.mintlify.site/language/settings.md). | | `with` | `with key E { ... }` | Anywhere a statement or a line goes: settings for its block only. See [with](https://pkhambat.mintlify.site/language/settings.md#with). | | Declaration | `steps fill = x-x-` | Anywhere. See [Names](#names). | | Line | `kick: x--x---` | In a block, or after `play`. See [Types](#types). | | Group | `(intro verse verse)` | In a block, or after `play`. What plays in order goes in brackets. See [Groups](https://pkhambat.mintlify.site/language/patterns.md#groups). | | `bar`, `every` | `bar 4 { ... }` | In a block, or after `play`. See [bar](https://pkhambat.mintlify.site/language/patterns.md#bar) and [every](https://pkhambat.mintlify.site/language/patterns.md#every). | | `play` | `play groove` | Top level only, which includes the top of a `with` there. See [play](https://pkhambat.mintlify.site/language/play.md). | ## Types Every value has one of five types. A line is a kit piece or an instrument, a colon and a value, and the name before the colon decides the value's type. So the drums and the pitched instruments never take each other's values: a `steps` name on `bass` is an error, and so is a `notes` name on `kick`. A `pattern` holds lines of both. | Type | A value is | Literal | Used | See | | - | - | - | - | - | | `steps` | Hits for one kit piece, as steps or beats. | `x--x---`, `2 4` | After a kit piece's colon. | [Steps](https://pkhambat.mintlify.site/drums/steps.md) | | `notes` | Notes for one instrument, one at a time, by name or by degree of the key. | `E---F# E-E--`, `1---3---5---` | After `notes` on an instrument's line. | [Notes](https://pkhambat.mintlify.site/pitched/notes.md) | | `chords` | Bars of chords. | `Am F\|C G` | After `chords` on an instrument's line. | [Chords](https://pkhambat.mintlify.site/pitched/chords.md) | | `pattern` | Lines that play together and repeat. | `{ kick: x--- }` | After `play`, on a line of its own, or in a group. | [Patterns](https://pkhambat.mintlify.site/language/patterns.md) | \| `block` | Lines that play together once. | `{ crash: 1 }` | After `play`, on a line of its own, or in a group. | [Blocks](https://pkhambat.mintlify.site/language/patterns.md#groups) | ## Names A declaration binds a name to a value: ` = `. The type is required. A name is accepted only where its type is, and only below its declaration. ```composer-nb theme={"theme":{"light":"github-light","dark":"github-dark"},"languages":{"custom":["/languages/composer-nb.json"]}} steps backbeat = 2 4 notes walk = 2 beats A1, 2 beats F1 | 2 beats C2, 2 beats G1 chords verse = Am F|C G pattern groove = { snare: backbeat hat: x- bass: notes walk piano: chords verse } play groove ``` A name of any type starts with a lowercase letter, then holds letters and digits, with a capital for each new word: `riff`, `partA`, `countIn`, `at100`. It is at least two characters long and not a Roman numeral, so it never reads as a step or a chord. Two names that differ only in their capitals are an error, including when one comes from a cell above. A name is defined once in a cell: defining it again is an error, inside a block too when it's defined outside it. A cell can define again a name from a cell above. ## Blocks A block is statements in braces, and it evaluates to a value. Where the block is decides its type. | Block | Evaluates to | | - | - | | After `pattern =`, `play`, `bar` or `every` | A `pattern`. | | After `with` and its settings | At the top of a cell, the statements in it. Anywhere else, a `pattern`, played with the settings. | | After a kit piece's colon | One `steps` value, from [layers](https://pkhambat.mintlify.site/drums/steps.md#layers). | | After an instrument's colon | [Layers](https://pkhambat.mintlify.site/pitched/notes.md#layers) of `notes` and `chords` that sound together. | The statements in a block start together, one per line. What plays in order goes in brackets: a [group](https://pkhambat.mintlify.site/language/patterns.md#groups) holds names, blocks, groups and lines, one after another, separated by spaces or new lines. Braces hold what plays together and brackets what plays in order, so a newline never decides between them. | Written | Plays | | - | - | | `{ ... }` on a line of its own | Together with the other lines. | | `({ ... } { ... })` | One after another. | | `intro verse`, `{ ... } outro` | An error: what plays in order goes in brackets. | ```composer-nb theme={"theme":{"light":"github-light","dark":"github-dark"},"languages":{"custom":["/languages/composer-nb.json"]}} play { ({ kick: x--- } { snare: x--- }) { hat: x- } } ``` The kick plays first and the snare after it, with the hats under both. A block holds one line per kit piece or instrument. To layer one, give its line a block. Where a line is decides whether it repeats. In a pattern, every line repeats until the pattern ends. Directly in a `play`, a line plays once. A value is not a loop: `x--x---` is seven steps, and the pattern around it does the repeating. So a `steps`, `notes` or `chords` value written as the same figure more than once is an error: `hat: x-x- x-x-` is `hat: x-`, and `chords Am F|Am F` is `chords Am F`. ## Lengths A length is a number and a unit, written in front of what it measures: `4 bars groove`, `2 beats rest`, `3 beats C2`, `every 3 steps`. Units are always plural, even after 1: `1 bars`. On a line, `...` is the length that is left of the block: `...rest`, `...x-`, `...G1`. On a [kit piece's line](https://pkhambat.mintlify.site/drums/steps.md#rests-and-lengths) a length repeats a figure, because a hit has no duration; on an [instrument's line](https://pkhambat.mintlify.site/pitched/notes.md#lengths) it holds one note, because a note has one. | Unit | Lasts | | - | - | | `steps` | One step: a sixteenth note, unless [`every`](https://pkhambat.mintlify.site/language/patterns#every) changes it. | | `beats` | A quarter note, in every time signature. | | `bars` | One bar of the current [`time`](https://pkhambat.mintlify.site/language/settings#time). | Any number can be arithmetic: `set tempo 60*2`, `every 1/3 beats`. ## Scope * A `set` applies from its line to the end of the cell. It goes only at the top of a cell; inside a block, settings go on a `with`. * A `with`'s settings apply to its block only, and what was set before comes back at its `}`. * A declaration applies from its line to the end of the cell, or of the block it is in, including a `with`'s. * A pattern is evaluated where it is played, with the settings in effect there, and with the names written above it: a later cell that defines a name again doesn't change what an earlier pattern plays. * The settings set at the top and the names declared there carry into other cells; a `with`'s never do. In the playground, a cell starts from the cells above it. In Jupyter, it starts from the cell named by [`after`](https://pkhambat.mintlify.site/jupyter#cells-that-continue). This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.