List Insert

Category: Lists

Inserts one value into an existing list variable. Use `where` to insert at the `END`, at the `START`, before a zero-based `INDEX`, or before a zero-based `FROM_END` position. If `where` is omitted, the block defaults to `END`. The `index` input is only used for `INDEX` and `FROM_END`. Out-of-range indices throw an error, and `FROM_END` cannot be used on an empty list.

Inputs

Input	Required	Value Kind	Types	Enum Values
name	yes	string	—	—
value	yes	expression	—	—
where	no	expression	enum-string	END, START, INDEX, FROM_END
index	no	expression	number	—

Notes

• Mutating statement for inserting one value into a list variable.
• where modes:
  • END: append to the end.
  • START: prepend at the start.
  • INDEX: insert before zero-based index from start; index may be equal to list length.
  • FROM_END: insert before the element at zero-based position from end (index=0 means before last element).
• If where is omitted, behavior defaults to END.
• index is only used for INDEX and FROM_END.
• listPush remains available as a convenience alias for listInsert(where=END).

Examples

Traverse Nested Sequences With Deduped Worklist

Traverses the active sequence and nested sequences through a pending/seen worklist so nested sequence refs are not processed twice.

kind: Pattern · format: runtime-dsl · validation: MCP fixture

Topics: sequence traversal, nested sequences, clip iteration, lists

Source: patterns/ex-sequence-traverse-nested-deduped.json

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