A personal account of evolving away from classical DDD Aggregate patterns toward functional composition and immutable data structures, driven by experience with Event Sourcing. The author explains how OOP-style aggregates made reasoning about business logic harder, how Event Sourcing naturally maps to state machines and functional patterns, and why entity+functions with immutability reduces cognitive load without creating an anaemic domain model. The post argues that composition of small blocks is the key to managing complexity, regardless of whether the approach is strictly 'functional'.
