Implicitly it means is not to model a program purely through types and how they interact with each other. In general you do start programming by defining domain

Implicitly it means is not to model a program purely through types and how they interact with each other. In general you do start programming by defining domain types (through a combination of structs, slices and maps), but it is up to the programmer to wire up the behaviors between them and not by expressing behaviors through the type system (ML-style functional programming) or by defining type hierarchies to model the real world (Java-style OOP).