Error handling

One of Rust's major goals is enabling the developer to write robust software. An essential component of this is advanced error handling. In this section, we will take a deeper look at how Rust does error handling. But before that, let's take a detour and look at some type theory. Specifically, we are interested in algebraic data types (ADT), types formed by combining other types. The two most common ADTs are sum and product types. A struct in Rust is an example of a product type. This name derives from the fact that given a struct, the range of its type is essentially the Cartesian product of the ranges of each of its components, since an instance of the type has values for all of its constituent types. In contrast, a sum type is when the ADT can assume the type of only one of its constituents. An example of this is an enum in Rust. While similar to enums...