Struct parametrizzate

A parameterized struct takes compile-time values in brackets, letting one definition become many type-safe, specialized containers. 📦

The T here is a type parameter. It stands in for whatever type you fill in when you actually create the struct.

When you use the struct, you supply the type in brackets, turning the generic blueprint into a concrete, fixed type.

The same blueprint gives you Box[Int], Box[Float64], and more, each a distinct type the compiler tailors for you.

Parameters need not be types. A numeric parameter can fix a size, like the length of a fixed-capacity array.

With size as a parameter, the compiler knows the exact layout in advance and can lay out memory with zero runtime guesswork.

Inside the struct, every method can use the parameters freely, so behavior adapts to the type or size you chose.

A Box[Int] simply will not accept a Float. The compiler enforces the parameter, catching mix-ups before the program ever runs.

A struct can list several parameters at once, combining types and sizes to describe exactly the container you need.

The built-in SIMD type is itself a parameterized struct: its element type and width are both compile-time parameters.

Parameterized structs give you Python-like generics with none of the overhead, since each version is specialized at compile time.

Recall what a parameterized struct can hold in its brackets.

You built parameterized structs: brackets hold types or sizes, one blueprint yields many specialized types, all checked and optimized at compile time. 🎯