Length

Returns the number of elements in a list.

Use this when

• You need to monitor or log how large an upstream batch is.
• You want to trigger a threshold check based on list size.
• You need to generate metadata (e.g. count, batch size) alongside the data.

What it does

Consumes one list per tick and emits a UInt64 equal to its element count. Input [0, 1, 2, 3, 4] becomes 5.

Inputs

Type	Description
[t]	A list of any type.

Outputs

Type	Description
UInt64	Number of list elements.

Parameters

This transformation takes no parameters.

Works best with

• Detection components that emit variable-length result lists per frame.
• Downstream thresholding, logging, or alerting components.

Caveats

• Output is always UInt64 — negative or signed counts are not possible.
• The list itself is consumed. Pair with a stream split upstream if you also need the elements.