Cheatsheet recap

One line per idea, in order. The pause-for-questions slide.

Idea	Remember
Two kinds of failure	if a user can hit it, it's Result. if it means the code is wrong, it's panic.
What triggers a panic	every one of these means a bug. fix the code.
When a panic fires	set `RUST_BACKTRACE=1` to see the line that crashed.
When a panic is right	panic on bugs. Result on expected failure.
The newtype trick	check at the door. trust everywhere after.
Reading a Result	two arms, both required. the compiler checks you handled both.
Handle it without match	match when it's complex. combinators when it's a one-liner.
Option vs Result	None says nothing. Err says why.
The ? operator	`?` = if Err, return it. if Ok, unwrap it.
What ? really does	`?` early-returns and converts the error.
The escape hatches	`expect` is `unwrap` with a reason. use it when `Err` can't happen.
Roll your own	one type. every failure mode. `From` makes `?` convert.
Let the crate write it	thiserror for libraries. anyhow for apps.

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