Expressions

Expressions may be used in two contexts:

value - when using the rngo.value JSON schema extension to generate realistic values
rate - when specifying a dynamic event rate in the stream rate field
duration - when setting the start and end of the simution.

Context

Each context has entrypoint methods that may be referenced in expressions without explicit qualification.

Method	Returns	Notes
`.streams`	`Object`[`Stream`]	A map of every stream in the workspace, keyed by its name.
`.data`	`DataCatalog`	A map of all enums provided by rngo. See Enums for more.
`.sim`	`Simulation`	The simulation state when the value is being generated.

Method	Returns	Notes
`.sim`	`Simulation`	The simulation state when the rate is being sampled.

Method	Args	Returns	Notes
`.daysAgo`	`days`: `Number`	`Timestamp`	Returns the number of days prior to the time when the expression is evaluated.
`.yearsAgo`	`years`: `Number`	`Timestamp`	Returns the number of years prior to the time when the expression is evaluated.
`.daysFromNow`	`days`: `Number`	`Timestamp`	Returns the number of days after the time when the expression is evaluated.
`.yearsFromNow`	`years`: `Number`	`Timestamp`	Returns the number of years after the time when the expression is evaluated.

Categorized data sets used to further narrow valid stream output beyond the JSON Schema definition.

See Data Catalog for more.

The state of a stream at the current point in the simulation. Stream extends Set so you can also call Set methods on a Stream instance.

Example: The set of all id values in the posts stream

stream.posts.last.id

Method	Returns	Notes
`.first`	`Value` \| `Null`	The first value generated by the stream, if any.
`.last`	`Value` \| `Null`	The last value generated by the stream, if any.

A collection of Values, that is potentially very large. Commonly used to specify rngo.value in a schema.

Example: A random value in the fullName enum

enum.fullName.random

Method	Returns	Notes
`.random`	`Value` \| `Null`	Returns a random value from the set, or null if empty.
`.unique`	`Value` \| `Null`	Returns a random value from the set that has not been previously returned. If all values have been returned, or if the set is empty, returns null.

Information about the current state of the simulation.

Example: The current time in the simulation

sim.now

Method	Returns	Notes
`.now`	`Timestamp`	The current UTC wall clock time within the simulation.
`.offset`	`Number`	The integer number of milliseconds since the simulation started.

Any value generated by a stream. It is a recursive union type with any of the following variants:

An ordered collection, generic over type T.

Method	Returns	Notes
`[{index}]`	`T` \| `Null`	Returns the value at the specified integer index, if ones exists.

An associated array, generic over value type T.

Method	Returns	Notes
`.{property}`	`T` \| `Null`	Returns the value of a named property, if it exists.

Either true or false.

A value that represents the absence of a value.

An integer or floating point number.

A sequence of Unicode characters.

An ISO 8901 UTC timestamp.

Method	Returns	Notes
`.string`	`String`	The ISO 8901 representation of the timestamp.