Structs
In this page we will discuss the struct type, its constructors, and its operations.
As an example, consider the first few lines of the file examples/wiki/structs.pf.
The struct type is defined in the newtype section of the script, as for example Person = struct(name string, age int). This creates the Person type and specifies the types of its fields. It also supplies us with a "short-form constructor" e.g. Person("Douglas", 42), which is just an ordinary function, and a "long-form constructor" e.g Person with name::"Joseph", age::22, where the fields come in any order. As we will see later on, functions can be overloaded, and this includes the short-form constructor.
User-defined types should be named in PascalCase.
As you can see, structs are indexed with square brackets, like everything else in Pipefish. This means that often you can treat them syntactically and semantically as though they were container types.
The things you index them by (name, age, pink) etc are first-class values, of type label.
The expressions that follow with in the long-form constructors, e.g. Person with name::"Joseph", age::22 are therefore also first-class values: name::"Joseph", age::22 is a tuple of pairs, where the [0]th element of each pair is a label.
In common with the list, map, and tuple types, we can use the with keyword to produce an altered copy of a struct:
Struct → doug with age::43
Person with (name::Douglas, age::43)
Struct → me with [pet, pink]::true
CatOwner with (name::Tim, pet::Cat with (name::Felix, nobelPrizes::0, pink::true))
Struct → joe with name::"Josephine", age::23
Person with (name::Josephine, age::23)
Struct →