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.
`.enums`	`Object`[`Set`]	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.

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.

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.