Cairo Numeric Types

Overview

Guide implementing production-quality custom numeric types (fixed-point, big integers, signed integers) in Cairo following Ekubo-style patterns.

Quick Use

• Read references/numeric-types.md before answering.
• Study Ekubo's i129 - the gold standard for signed integers in Cairo.
• Use constructor functions to enforce invariants (e.g., no negative zero).
• Provide both checked (returns Option) and unchecked (panics) API variants.
• Implement standard traits: PartialEq, PartialOrd, Add, Sub, Mul, Neg, Zero, One.

Response Checklist

Invariant Enforcement

• Use a private constructor function that enforces invariants (Ekubo i129 pattern).
• Example: fn i256_new(mag: U256, neg: bool) -> I256 { I256 { mag, neg: neg && !u256_is_zero(mag) } }
• Never allow invalid states like negative zero.