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Swift Academy · Lesson

Scoped APIs & readability patterns

Apply scoped APIs and naming patterns for DSLs: namespace tokens, group with helpers, and keep blocks small and explicit.

Scoped APIs & readability patterns is a free Swift Academy lesson on CoddyKit — lesson 2 of 3. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Swift Academy learning path, one of 3 lessons in the course, and your progress syncs across the web and the CoddyKit app.

Why scope a DSL?

Readable DSLs limit what you can do in a block and name things clearly. Use namespaces, small helpers, and grouping to keep intent obvious.

Namespace pattern

Placing tokens under R narrows the surface and prevents clashes with app symbols; calls stay short and scannable.

struct Route { let method: String; let path: String }

// Namespace instead of global free functions
enum R {
    static func GET(_ path: String) -> Route  { Route(method: "GET",  path: path) }
    static func POST(_ path: String) -> Route { Route(method: "POST", path: path) }
}

@resultBuilder
struct RoutesBuilder {
    static func buildBlock(_ parts: Route...) -> [Route] { parts }
}

func routes(@RoutesBuilder _ content: () -> [Route]) -> [Route] { content() }

let table = routes {
    R.GET("/home")
    R.POST("/upload")
}
for r in table { print("\(r.method) \(r.path)") }

Grouping helper

Use a small grouping helper to add context (prefix, tags) without repeating yourself; the block remains tidy.

// Group routes by a shared prefix using a helper
func section(_ prefix: String, @RoutesBuilder _ content: () -> [Route]) -> [Route] {
    content().map { Route(method: $0.method, path: prefix + $0.path) }
}

let grouped = routes {
    R.GET("/health")
    section("/admin") {
        R.GET("/dashboard")
        R.POST("/upload")
    }
}
for r in grouped { print("\(r.method) \(r.path)") } // /admin/* prefixed

Separate concerns

Prefer small builders for separate concerns (routes vs middlewares). Each block exposes only what it needs.

// A separate builder for middlewares (keeps concerns isolated)
struct Middleware { let name: String }

@resultBuilder
struct MiddlewareBuilder {
    static func buildBlock(_ parts: Middleware...) -> [Middleware] { parts }
}

enum M {
    static func log(_ name: String) -> Middleware { Middleware(name: "log:\(name)") }
    static func auth() -> Middleware { Middleware(name: "auth") }
}

func middlewares(@MiddlewareBuilder _ content: () -> [Middleware]) -> [Middleware] { content() }

let mw = middlewares {
    M.log("requests")
    M.auth()
}
print(mw.map(\.name))

Readability tips

Patterns:

  • Use short verbs: GET, POST, auth.
  • Keep one action per line.
  • Prefer flat blocks; nest only to add context.
  • Give explicit labels in helpers (e.g., prefix:).

Validation helper

Provide tiny validation helpers to keep blocks correct. Fail fast with helpful messages.

// Add a simple validator to catch mistakes early
func validate(_ routes: [Route]) -> [String] {
    var issues: [String] = []
    let seen = Set(routes.map { $0.method + " " + $0.path })
    if seen.count != routes.count { issues.append("Duplicate route detected") }
    if routes.contains(where: { !$0.path.hasPrefix("/") }) {
        issues.append("Paths must start with /")
    }
    return issues
}

let issues = validate(grouped)
print(issues.isEmpty ? "OK" : "Issues: \(issues)")

Scoped API pattern

Quick check: Which choice makes a DSL block safer and clearer?

Recap

Recap: Scope your DSL with namespaces, use small grouping helpers, keep blocks focused, and validate early for safer, more readable code.

Frequently asked questions

Is the “Scoped APIs & readability patterns” lesson free?

Yes — the full text of “Scoped APIs & readability patterns” is free to read here on the web, and the Swift Academy course includes 3 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Swift Academy course, upgrade to CoddyKit PRO.

What will I learn in “Scoped APIs & readability patterns”?

Apply scoped APIs and naming patterns for DSLs: namespace tokens, group with helpers, and keep blocks small and explicit. You practise Swift Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start Swift Academy?

No prior experience is required. Swift Academy on CoddyKit is structured for beginners through advanced learners; this is — lesson 2 of 3, so you can start here or from the beginning and move at your own pace.

How long does the “Scoped APIs & readability patterns” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

Can I write and run code in this Swift Academy lesson?

Yes. Every Swift Academy lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.

All lessons in this course

  1. Building mini-DSLs with result builders
  2. Scoped APIs & readability patterns
  3. Practical examples without UI frameworks
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