# Collections

## `Sequence`

The most primitive collection: a series of expressions separated by a `,`.

MathJSON Latex
`["Sequence", "x", "y"]` \( x, y \)
`["Sequence", ["Add", "x", 1], "y"]` \( x + 1, y \)

## `Sequence2`

A series of expressions separated by a `;`.

MathJSON Latex
`["Sequence2", "x", "y"]` \( x; y \)
`["Sequence2", ["Sequence", "a", "b"], "y"]` \(a, b; y \)

## `Set`

An unordered collection of unique elements.

MathJSON Latex
`["Set", "x", "y"]` \( \lbrack x, y\rbrack \)

## `List`

An ordered collection of elements.

Use to represent a data structure, as opposed to `Parentheses` or `Sequence`.

MathJSON Latex
`["List", "x", "y", "7", "11"]` \([x, y, 7, 11]\)
`["List", "x", "Nothing", "y"]` \([x,y]\)

## `Parentheses`

One or more expressions in a sequence, enclosed with parentheses.

Use to represent function arguments, or to group arithmetic expressions.

MathJSON Latex
`["Parentheses", "x", "y", "7", "11"]` `(x, y, 7, 11)`
`["Parentheses"]` `()`
`["Parentheses", "a", "b", "c"]` `(a, b, c)`
`["Parentheses", ["Sequence, "a", "b"], ["Sequence", "c", "d"]]` `(a, b; c, d)`
`["Sequence", "a", ["Parentheses", "b", "c"]]` `a, (b, c)`