Playground Generator (my solution to https://gist.github.com/chriseidhof/b0fb6b0a4cf370e873dc56ee0a6ad42d)

playground-generator.swift

enum Block {
	case code(String)
	case text(String)
	case header(String)
}

enum PlaygroundElement {
	case code(String)
	case documentation([Block])
}

func playground(blocks : [Block]) -> [PlaygroundElement] {
	return blocks.reduce([], appendBlock)
}

func appendBlock(to elements : [PlaygroundElement], block : Block) -> [PlaygroundElement] {
	switch block {
	case .code(let code): return elements + [.code(code)]
	case .text(let text): return updateDocumentation(result: elements, newBlock: .text(text))
	case .header(let header): return updateDocumentation(result: elements, newBlock: .header(header)) 
	}
}

func updateDocumentation(result : [PlaygroundElement], newBlock : Block) -> [PlaygroundElement] {
	if case .documentation(let blocks)? = result.last {
		let updatedDocumentation = PlaygroundElement.documentation(blocks + [newBlock])
		return Array(result.dropLast()) + [updatedDocumentation]
	} else {
		return result + [.documentation([newBlock])]
	}
}

let sample : [Block] = [.code("swift sample code"), .header("My Header"), .text("Hello"), .code("more"), .text("text")]

let result: [PlaygroundElement] = [
	.code("swift sample code"),
	.documentation([Block.header("My Header"), .text("Hello")]),
	.code("more"),
	.documentation([.text("text")])
]