Domain Modeling Made Functional

Seeing Patterns in a Domain Model

Although each domain model is different, many patterns occur repeatedly.

Let’s look at some of the patterns of a typical domain and see how we can relate components of our model to them.

• Simple values. These are the basic building blocks represented by primitive types such as strings and integers. But note that they are not actually strings or integers. A domain expert does not think in terms of int and string, but instead thinks in terms of OrderId and ProductCode—concepts that are part of the ubiquitous language.

• Combinations of values with AND. These are groups of closely linked data. In a paper-based world, these are typically documents or subcomponents of a document: names, addresses, orders, and so forth. ...