Functional programming and domain-driven design might not seem to be a good match, but in fact functional programming can be an excellent approach to designing decoupled, reusable systems with a rich domain model. This workshop will show you why.
This will be a hands-on workshop designed for beginners in functional programming. We'll do lots of exercises and build some small projects that take us all the way from high-level design to low-level implementation.
This will be especially useful for people learning functional programming -- all concepts used in the workshop will be explained. Previous development experience is recommended.
- The concepts of functional programming
- How to represent the nouns and verbs of a domain using types and functions
- How to decouple the pure domain logic from the outside world
- How to ensure that constraints and business rules are captured in the design
- How to represent state transitions in the domain model
- How to build a business workflow from smaller components
- How to handle errors as part of the domain
By the end of the workshop you'll know how to build working solutions with rich domain models, using only functional programming techniques.
Introduction to functional programming
- Functions and types
- Composition as the fundamental principle
Overview of DDD principles
- The importance of bounded contexts
- Persistence ignorance
- Onion/Hexagonal architecture and how this works with functional programming
Modeling requirements with algebraic types
- Records, choices, and functions
- Modeling constraints
- Modeling states
Programming a workflow
- Keeping IO at the edges
- Handling domain errors
- Composing complex functions
Evolving the domain
- Dealing with changes in requirements
We will be using F# as our development language. No experience with F# needed.
Please install the F# compiler and an F#-friendly editor such as Visual Studio Code using the instructions at fsharp.org.