cairo-custom-data-structures

name	cairo-custom-data-structures
description	Explain how to build custom data structures in Cairo using structs, traits, and dictionaries; use when a request involves implementing mutable collections (like a vector) or handling Destruct/Drop with Felt252Dict.

Cairo Custom Data Structures

Overview

Guide users through building mutable data structures on top of dictionaries and traits, including proper destruction.

Quick Use

• Read references/custom-data-structures.md before answering.
• Emphasize that arrays are immutable; use Felt252Dict for mutable storage.
• Call out Destruct implementations for structs containing dictionaries.

Response Checklist

• Define a trait interface for the structure's operations.
• Store values in a Felt252Dict and track len separately when emulating vectors.
• Use Nullable when storing generic T in a dict.
• Implement Destruct to squash() dictionaries.

Example Requests

• "How do I build a mutable vector in Cairo?"
• "Why does my struct with a dictionary need Destruct?"
• "How can I update a value by index?"

Cairo by Example

• Dictionaries
• Drop and Destruct
• Testcase: linked-list