---
minutes: 3
course: Fundamentals
session: Day 4 Morning
target_minutes: 180
---

# Welcome to Day 4

Today we will cover topics relating to building large-scale software in Rust:

- Iterators: a deep dive on the `Iterator` trait.
- Modules and visibility.
- Testing.
- Error handling: panics, `Result`, and the try operator `?`.
- Unsafe Rust: the escape hatch when you can't express yourself in safe Rust.

## Schedule

{{%session outline}}
