A transaction log

First, a list has to be defined—in Rust, lacking a null type, each item is chained to the next by an Option property. The Option instances are enumerations that wrap either the value, in this case a heap reference (such as a Box, Rc, and so on), or none—Rust's typed null equivalent. Why? Let's find out!

Creating a prototypical implementation to explore a certain aspect is always a good idea, especially since the compiler often provides excellent feedback. Accordingly, an implementation of an integer list is the first step. How about this struct for each list element?

Have a look at the following code snippet:

struct Node {
    value: i32,
    next: Option<Node>
}

For practical considerations, it needs a way to know where to start and the length of the list. Considering the planned append operation, a reference to the end (tail) would be useful too:

struct TransactionLog {
    head: Option<Node>, 
    tail: Option<Node>,
    pub length...