--- title: "Type Safety and Money" url: https://daily.dev/posts/type-safety-and-money-egzghpu5w source_url: https://verraes.net/2016/02/type-safety-and-money type: article source: "Mathias Verraes" published: 2026-06-17T11:25:36.669Z updated: 2026-06-17T11:28:31.590Z tags: ["general-programming", "domain-driven-design"] reading_time: 17 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. # Type Safety and Money **[Mathias Verraes](https://daily.dev/sources/verraes)** · 17 min read · 0 upvotes · 0 comments ## Summary A design walkthrough of modeling money with type safety in mind, using Domain-Driven Design principles. Starting from a basic Fowler-style Money value object, the author iteratively refines the design by introducing PreciseMoney and RoundedMoney as distinct types, currency-specific subtypes (e.g., PreciseEUR, RoundedBTC), and a ConversionRate value object to separate side-effectful exchange rate fetching from pure conversion logic. Key benefits highlighted include compiler-enforced contracts, reduced test burden through declarative typing, Single Responsibility Principle adherence, and minimalist interfaces. The post also touches on Bounded Contexts, the Repository pattern for value objects, and extends the type-safety concept to timezone handling. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Similar posts on daily.dev - [Why You Should Never Use Floating Point for Money](https://daily.dev/posts/why-you-should-never-use-floating-point-for-money-mf4k3pznd) · Sergio Lema · 17 upvotes · 6 comments --- Tags: [#general-programming](https://daily.dev/tags/general-programming), [#domain-driven-design](https://daily.dev/tags/domain-driven-design) [View this post on daily.dev](https://daily.dev/posts/type-safety-and-money-egzghpu5w)