Rust has no exceptions. A function that can fail says so in its return type, and the caller must deal with it. At first, this feels like extra work. After a month, code in other languages starts to look as if it is hiding something.
Two kinds of failure
Rust separates failures you expect from failures that mean the program is wrong.
- A file is missing, a request times out, the user types a letter where a number should be. These are normal, and you handle them with
Result. - An index is out of range, or a value that must exist does not. These are bugs, and the program stops with a
panic!.
Do not use panics for things that can happen in normal operation. Do not use Result for things that can never happen.
