# Core

## Constants

### Missing

This symbol is used when a required expression is not present.

MathJSONLatex
["Divide", 2, "Missing"]\frac{2}{\placeholder{}}

### Nothing

This symbol is used when an optional expression is not present.

MathJSONLatex
["List", 2, "Nothing", 3]\lrback 2,,3 \rbrack

### None

This symbol is used to indicate that out of multiple possible values, none apply.

### All

This symbol is used to indicate that out of multiple possible values, all apply.

## Functions

### About

["About",symbol]

Return information about a symbol such as its domain, its attributes, its value, etc…

### Domain

["Domain",expression]

Return the domain of the expression.

### Evaluate

["Evaluate",expression]

Apply a sequence of definitions to an expression in order to reduce and simplify it.

An evaluation can consist of:

• a computation
["Evaluate", ["Add", 2, 3]]
// ➔ 5

• an execution
["Evaluate", ["Length", ["List", 5, 7]]]
// ➔ 2

• a simplification
["Evaluate", ["Add", 2, ["Add", "x", 3]]]


### Identity

Always return its argument.

MathJSONLatex
["Identity", "x"]\operatorname{id}(x)
"Identity"\operatorname{id}

### InverseFunction

Return the inverse function of its argument.

MathJSONLatex
["InverseFunction", "Sin"]\sin^{-1}

### Lambda

["Lambda",variables,expression]

Create a Lambda-function, also called anonymous function.

The first argument is a symbol or a list of symbols which are the bound variables of the Lambda-function.

The second argument is an expression expressed as a function of the bound variables of the Lambda-function.

To apply a Lambda-function to some arguments, use:

[["Lambda", ["List", "x"], ["Multiply", "x", "x"]], "3"]
// ➔ 9


### Latex

["Latex",expr-1,expr-2, ...expr-n]

• expr-n: one or more expressions
• Returns a string, a Latex string corresponding to the input expressions.
["Latex", ["Divide", "Pi", 2]]
// ➔ "'\frac{\pi}{2}'"


If the argument is a string, it is interpreted as a Latex token or fragment:

• <{>: begin group
• <}>: end group
• <space>: blank space