In a couple recent episodes, we introduced the idea of domain specific languages, often abbreviated DSLs, which are languages that are highly tuned to a specific task. We then introduced the idea of embedded DSLs (or EDSLs), which are domain specific languages that are hosted, or written, in a more general purpose language, like Swift.

To get comfortable with the idea, we embedded some basic arithmetic in the Swift type system. Using a DSL helped us separate the pure, data-driven description of a domain problem from the impure, run-time interpretation of that data.

But arithmetic was a bit of a toy example, though, so today we’re going to embed a more real-world domain problem in Swift, HTML, by building the same DSL that we use to power the Point-Free web site!