Parametric type is a core language feature that's used to materialize data types with parameters. It is a very powerful technique because the same object structure can be reused for different data types in its fields. In this section, we will demonstrate how parametric types can be applied effectively.
When designing applications, we often create composite types to conveniently hold multiple field elements. In its simplest form, composite types only serve as the containers of fields. As we create more and more composite types, it may become clear that some of these types look almost the same. Furthermore, the functions that operate on these types may be very similar as well. We could end up with a lot of boilerplate code. Wouldn't it be cool to have a template that allows us to customize a general composite type for a specific use? ...
