--- title: "A Functional Foundation for CQRS/ES" url: https://daily.dev/posts/a-functional-foundation-for-cqrs-es-wxkl8yr24 source_url: https://verraes.net/2014/05/functional-foundation-for-cqrs-event-sourcing type: article source: "Mathias Verraes" published: 2026-06-17T11:25:44.034Z updated: 2026-06-17T11:27:49.254Z tags: ["architecture", "functional-programming", "domain-driven-design"] reading_time: 6 upvotes: 0 comments: 0 language: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # A Functional Foundation for CQRS/ES **[Mathias Verraes](https://daily.dev/sources/verraes)** · 6 min read · 0 upvotes · 0 comments ## Summary CQRS and Event Sourcing can be modeled as a set of four pure functions: Protection (aggregate handles commands given history, producing events), Interpretation (projecting events into read-model state), Intention (user converts state into commands), and Automation (process managers convert events into commands). The functional framing highlights referential transparency and separation of concerns. A 2016 update extends the model to include Queries and Subscriptions, expressing the full architecture in Haskell-style type signatures. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Event Sourcing: Simple is often enough](https://daily.dev/posts/event-sourcing-simple-is-often-enough-ijvzsfk43) · We Are .NET · 0 upvotes · 0 comments - [CQRS and Event Sourcing in TypeScript: A Production Walkthrough](https://daily.dev/posts/cqrs-and-event-sourcing-in-typescript-a-production-walkthrough-z0puzlhgn) · Atomic Spin · 3 upvotes · 0 comments --- Tags: [#architecture](https://daily.dev/tags/architecture), [#functional-programming](https://daily.dev/tags/functional-programming), [#domain-driven-design](https://daily.dev/tags/domain-driven-design) [View this post on daily.dev](https://daily.dev/posts/a-functional-foundation-for-cqrs-es-wxkl8yr24)