Monolithic Entities: The Basics

The simplest form of an entity in Flint is a monolithic entity, where data and functionality are defined together in one place.

Example:

entity Counter:
    data:
        int value;

    func:
        def increment(int amount):
            value += amount;

        def get_value() -> int:
            return value;

    Counter(value); // Constructor to initialize the entity

Key Points:

1. Structure: Entities have two main sections:
   • Data: Variables that store the state of the entity.
   • Func: Functions that operate on the data.
2. Constructor: The constructor initializes the entity. Its parameters must match the declared fields in the data section.
3. Use Case: Monolithic entities are straightforward and perfect for small projects or tightly coupled logic.
4. Immutability: The data saved inside an entity cannot be accessed outside of func modules. So, when Entity E uses a func module which acts on data D the data of D cannot be accessed via an instance of E. This means that e.value is impossible. For all operations on data, getters and setters must be provided inside the func module.

Usage Example:

def main():
    Counter counter = Counter(0);
    counter.increment(5);
    print($"Counter value: {counter.value}");
    counter.reset();
    print($"Counter value after reset: {counter.value}");

Monolithic entities are Flint’s simplest abstraction, but their true power emerges as we explore func modules.