Version: ðŸš§ 2024-06 ðŸš§

# Literals

(some literal expressions are also described in data types)

A literal is a way to specify an unnamed constant value corresponding to a given data type. GAML supports various types of literals for often â€” or less often â€” used data types.

## Simple Typesâ€‹

Values of simple (i.e. not composed) types can all be expressed using literal expressions. Namely:

• bool: `true` and `false`.
• int: decimal value, such as `100`, or hexadecimal value if preceded by `'#'` (e.g. `#AAAAAA`, which returns the int `11184810`)
• float: the value in plain digits, using `'.'` for the decimal point (e.g. `123.297`)
• string: a sequence of characters enclosed between quotes (`'my string'`) or double quotes (`"my string"`)

## Literal Constructorsâ€‹

Although they are not strictly literals in the sense given above, some special constructs (called literal constructors) allow the modeler to declare constants of other data types. They are actually operators but can be thought of literals when used with constant operands.

• pair: the key and the value separated by `::` (e.g. `12::'abc'`)
• list: the elements, separated by commas, enclosed inside square brackets (e.g. `[12,15,15]`)
• map: a list of pairs (e.g. `[12::'abc', 13::'def']`)
• point: 2 or 3 int or float ordinates enclosed inside curly brackets (e.g. `{10.0,10.0,10.0}`)

## Universal Literalâ€‹

Finally, a special literal, of type `unknown`, is shared between the data types and all the agent types (aka species). Only `bool`, `int` and `float`, which do not derive from `unknown`, do not accept this literal. All the others will accept it (e.g. `string s <- nil;` is ok).

• unknown: `nil`, which represents the non-initialized (or, literally, unknown) value.