100 exercises to learn Rust

book/src/05_ticket_v2/15_outro.md

@@ -0,0 +1,22 @@
+# Wrapping up
+
+When it comes to domain modelling, the devil is in the details.  
+Rust offers a wide range of tools to help you represent the constraints of your domain directly in the type system,
+but it takes some practice to get it right and write code that looks idiomatic.
+
+Let's close the chapter with one final refinement of our `Ticket` model.  
+We'll introduce a new type for each of the fields in `Ticket` to encapsulate the respective constraints.  
+Every time someone accesses a `Ticket` field, they'll get back a value that's guaranteed to be valid—i.e. a 
+`TicketTitle` instead of a `String`. They won't have to worry about the title being empty elsewhere in the code:
+as long as they have a `TicketTitle`, they know it's valid **by construction**.  
+
+This is just an example of how you can use Rust's type system to make your code safer and more expressive.
+
+## References
+
+- The exercise for this section is located in `exercises/05_ticket_v2/15_outro`
+
+## Further reading
+
+- [Parse, don't validate](https://lexi-lambda.github.io/blog/2019/11/05/parse-don-t-validate/)
+- [Using types to guarantee domain invariants](https://www.lpalmieri.com/posts/2020-12-11-zero-to-production-6-domain-modelling/)