---
title: swift-primitives/swift-render-primitives
framework: Swift Package Catalog
role: article
path: packages/swift-primitives/swift-render-primitives
---

# swift-primitives/swift-render-primitives

Format-independent rendering primitives for Swift — a `Render` namespace of composable view trees and a witness-struct `Render.Context` that drives any output backend, with zero platform dependencies.

## Quick Start

`Render.View` describes *what* to render; `Render.Context` describes *where* it goes. A view tree is format-independent — the same tree renders to HTML, PDF, plain text, or an in-memory event log. The context is a witness struct built from closures, so a backend is just a set of handlers; there is no protocol to conform to and no subclass to write.

```swift import Render_Primitives

// A leaf view that emits a single run of text. struct TextRun: Render.View, Sendable {     let value: String     init(_ value: String) { self.value = value }

typealias Body = Never     var body: Never { fatalError("TextRun is a leaf view; body is never evaluated") }

static func _render(_ view: borrowing Self, context: inout Render.Context) {         context.text(view.value)     } }

// A backend is a set of closures — here, a minimal HTML emitter. var html = "" var context = Render.Context(     text: { html += $0 },     break: .init(line: { html += "<br>" }, thematic: { html += "<hr>" }, page: {}),     image: { source, alt in html += #"<img src="\#(source)" alt="\#(alt)">"# },     push: .init(         block: { _, _ in html += "<p>" },         inline: { _, _ in html += "<em>" },         list: { _, _ in html += "<ul>" },         item: { html += "<li>" },         link: { html += #"<a href="\#($0)">"# }     ),     pop: .init(         block: { html += "</p>" },         inline: { html += "</em>" },         list: { html += "</ul>" },         item: { html += "</li>" },         link: { html += "</a>" }     ) )

// Compose two views with Render.Pair and drive them through the context. context.render(     Render.Pair(first: TextRun("Hello, "), second: TextRun("world!")) ) print(html)   // Hello, world! ```

Composition is declarative through `Render.Builder` (`buildBlock`, `buildOptional`, `buildEither`, `buildArray`), which lowers `if`/`else` to `Render.Conditional`, `for` loops to arrays, and sibling content to a flat `Render._Tuple`. The flat tuple keeps nesting depth at O(1), so deeply composed trees render iteratively without overflowing the stack. `Render.Pair` and `Render.Conditional` are `~Copyable`-aware, so move-only views compose without forcing a copy.

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## Installation

```swift dependencies: [     .package(url: "https://github.com/swift-primitives/swift-render-primitives.git", branch: "main") ] ```

```swift .target(     name: "App",     dependencies: [         .product(name: "Render Primitives", package: "swift-render-primitives"),     ] ) ```

Requires Swift 6.3.1 and macOS 26 / iOS 26 / tvOS 26 / watchOS 26 / visionOS 26 (or the matching Linux / Windows toolchain).

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## Architecture

Three library products. No dependencies.

| Product | Target | Purpose | |---------|--------|---------| | `Render Primitive` | `Sources/Render Primitive/` | The `Render` namespace: `Render.View`, the witness-struct `Render.Context` with its `push` / `pop` / `break` / `speculative` operations, the `Render.Builder` result builder, the composition types `Render._Tuple`, `Render.Pair`, `Render.Conditional`, `Render.Group`, `Render.Empty`, `Render.Indirect`, and the value vocabulary `Render.Action`, `Render.Semantic`, `Render.Style`. | | `Render Primitives` | `Sources/Render Primitives/` | Umbrella that re-exports `Render Primitive`. | | `Render Primitives Test Support` | `Tests/Support/` | A recording context and leaf views for testing consumers' rendering code. |

Foundation-free.

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## Platform Support

| Platform | Status | |----------|--------| | macOS 26 | Full support | | Linux | Full support | | Windows | Full support | | iOS / tvOS / watchOS / visionOS | Supported |

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## Community

<!-- BEGIN: discussion --> <!-- Discussion thread created at publication. --> <!-- END: discussion -->

## License

Apache 2.0. See [LICENSE.md](LICENSE.md).

## Package Metadata

Repository: swift-primitives/swift-render-primitives

Default branch: main

README: README.md