How to use nef library?

As you know, from Xcode 11, you can integrate package dependencies using Swift Package Manager (SPM) to share code between projects or even use third-party libraries. You can read more about it in Apple’s article Adding package dependencies to your app

Starting on nef version 0.4, we have modularized the core so that you can use nef as in library as in your macOS projects. Taking advantage of the integration of SPM in Xcode, you can easily import nef in your project.

Just choose as package repository and Xcode will do the rest.

Add nef library to Xcode as a dependency

Once Xcode resolves the dependencies, you can import wherever you want, as a native framework:

 import nef

That’s all! The power of nef runs into your project. Cool!


nef library provides several utilities to work with Markdown, Jekyll and Carbon. It enables easy access to render Markdown files, Jekyll content and Carbon images in a functional way.


If you need to render the content of a Playground page, or anything else that combine markup formatting and code.

 nef.Markdown.render(content: String, toFile file: URL) -> IO<nef.Error, URL>


When you need to render content that combines Markdown, code, and nef commands with the Jekyll style.

 nef.Jekyll.render(content: String, toFile file: URL, permalink: String) -> IO<nef.Error, URL>


nef lets you render Carbon images given a CarbonModel; it is the configuration with the code and style.

 nef.Carbon.render(carbon: CarbonModel, toFile file: URL) -> IO<nef.Error, URL>

You can find other helpers for drawing Views with a Carbon style.

 nef.Carbon.view(with configuration: CarbonModel) -> CarbonView
 nef.Carbon.request(with configuration: CarbonModel) -> URLRequest


In this section, we will see how we can use the nef API. As an example, we will take advantage of the Carbon API.

Firstly, we need to create a model with Carbon configuration and the style.

 let model = CarbonModel(code: """
                               import nef
                               let library = 'nef library is super cool!'
                         style: CarbonStyle(background: .bow,
                                            theme: .dracula,
                                            size: .x1,
                                            fontType: .firaCode,
                                            lineNumbers: true, watermark: true))

We could render a carbon image from this configuration

 let io = nef.Carbon.render(carbon: model, toFile: output)

You will receive an IO; it lets you suspend the execution of the sides effects, in the example to create the Carbon image. That way, we could combine and compose with other operations. It is powerful!

When we want to execute it, we only need to invoke an unsafe operation:

 let either = io.unsafeRunSyncEither() { url in
    // TODO
 }.mapLeft { error in
    // TODO


In the output path, you can find the result:

Example: use of nef library