At-Maps

At-maps are multimaps that can be declared and used in format strings. Their keys can be associated with multiple values.

When used with functions that accept at-maps, the objects are used directly. When converted to a string, at-maps use the stringified version of the first available value. This behavior enables using at-maps to represent basic logic branches.

For example, the following expressions have equivalent results:

$IfElse($token $token default)
@($token:$token;1:default)
@($token;default)

Defining At-Maps

At-maps are defined with an @ sign and enclosed by parentheses. Keys and values are separated by a colon, and entries are separated by a semicolon.

@()
An empty at-map. Evaluates to the empty string and (like the empty string) is treated as falsy in boolean operations.

@(key:value)
An at-map with a single key-value pair. Evaluates to value. If key is falsy or evaluates the empty string, it is not added to the at-map. Falsy values are allowed.

@(value)
Specifies an at-map with value as both the key and value. For example, @(1) is equivalent to @(1:1).

@(A;B)
@(A;B:C)
@(A:B;C)
@(A:B;C:D)
Specifies an at-map with multiple values. The described syntaxes can be combined as desired.

@($_map:value)
(where $_map is an at-map) Specifies an at-map with all of the values of $_map mapped to value. For example, @(@(A;B):value) is equivalent to @(A:value;B:value).