Type Aliases

Pint provides the ability to declare a type alias to give an existing type another name. For this we use the type keyword. For example, we can create the alias Balance to int like so:

type Balance = int;

Now, the alias Balance is a synonym for int. Values that have the type Balance will be treated the same as values of type int:

let x: int = 5;
let y: Balance = 5;
constraint x == y;

Because Balance and int are the same type, we can compare values of both types.

Many programming languages offer the concept of a "struct" which lets you package together and name multiple related values that make up a meaningful group. While Pint does not offer a special struct construct, it does offer a way to name a tuple, name its fields, and access its elements as if it were a struct.

To define a struct-like tuple (which we will just call a struct going forward), we use the type keyword followed by the name chosen for the tuple. We then use the = operator to bind the new type name to a tuple type with all of its fields named.

For example:

type User = {
    status: bool,
    address: b256,
    balance: int,
};

To use a struct after we’ve defined it, we create an instance of that struct by specifying concrete values for each of the fields. We create an instance using the same tuple expression syntax: curly brackets containing key: value pairs, where the keys are the names of the fields and the values are the data we want to store in those fields. We don’t have to specify the fields in the same order in which we declared them in the struct. In other words, the struct definition is like a general template for the type, and instances fill in that template with particular data to create values of the type. For example, we can declare a particular User as shown below:

let user1: User = {
    status: true,
    address: 0x1111111111111111111111111111111111111111111111111111111111111111,
    balance: 42,
};

To get a specific value from a struct, we use the dot notation similarly to tuples. For example, to access this user's balance, we use user1.balance.

The Book of Pint

Type Aliases

Defining structs using type

Defining structs using `type`