Swift-Jupyter

A Jupyter Kernel for Swift, enabling interactive Swift programming in Jupyter notebooks.

Quick Start (Google Colab)

The easiest way to try Swift in Jupyter is with Google Colab:

1. Click the Open in Colab badge above
2. Run the first cell to install Swift (~3-5 minutes)
3. Go to Runtime → Change runtime type → Swift
4. Run Swift code!

Or create a new Colab notebook and run:

!curl -sL https://raw.githubusercontent.com/pedronahum/swift-jupyter/main/install_swift_colab.sh | bash

Features

• Swift Execution: Variables, functions, structs, classes, protocols
• Automatic Differentiation: Built-in Differentiable protocol and gradient() function
• SwiftPM Packages: Install packages with %install directive
• Magic Commands: %help, %who, %reset, %timeit
• Expression Display: Values display automatically like Python notebooks
• PythonKit: Access matplotlib, numpy, pandas via Swift

Example: Differentiable Programming

struct Model: Differentiable {
    var w: Float
    var b: Float
    func applied(to input: Float) -> Float {
        return w * input + b
    }
}

let model = Model(w: 4, b: 3)
let input: Float = 2
let (gradModel, gradInput) = gradient(at: model, input) { model, input in
    model.applied(to: input)
}

print(gradModel)  // Model.TangentVector(w: 2.0, b: 1.0)
print(gradInput)  // 4.0

Local Installation

macOS

# Install Jupyter
/usr/bin/python3 -m pip install --user jupyter ipykernel

# Clone and register
git clone https://github.com/pedronahum/swift-jupyter.git
cd swift-jupyter
/usr/bin/python3 register.py --sys-prefix \
  --swift-toolchain /Library/Developer/Toolchains/swift-latest.xctoolchain/usr

# Start Jupyter
jupyter notebook

Important: Use system Python (/usr/bin/python3), not conda or virtualenv.

Linux (Ubuntu 22.04+)

# Install Swift via swiftly
curl -L https://swiftlang.github.io/swiftly/swiftly-install.sh | bash
swiftly install main-snapshot

# Create virtual environment
python3 -m venv venv
source venv/bin/activate
pip install jupyter ipykernel

# Clone and register
git clone https://github.com/pedronahum/swift-jupyter.git
cd swift-jupyter
python3 register.py --sys-prefix --use-swiftly-toolchain

# Start Jupyter
jupyter notebook

Installing Swift Packages

Use the %install directive in the first cell:

%install '.package(url: "https://github.com/pvieito/PythonKit", branch: "master")' PythonKit

Then import and use:

import PythonKit

let np = Python.import("numpy")
let plt = Python.import("matplotlib.pyplot")

let x = np.linspace(0, 10, 100)
let y = np.sin(x)
plt.plot(x, y)
plt.show()

Magic Commands

Command	Description
%help	Show available commands
%lsmagic	List all magic commands
%who	List defined variables
%reset	Clear all state
%timeit <code>	Time code execution
%env [VAR[=VALUE]]	Show/set environment variables
%swift-version	Show Swift toolchain information
%load <file>	Load and execute a Swift file
%save <file>	Save execution history to file
%history [-n N]	Show execution history
%install	Install Swift packages
%enable_completion	Enable code completion
%disable_completion	Disable code completion

Pre-compiled Library Directives

For pre-compiled Swift libraries that cannot use %install (due to SPM's unsafeFlags restrictions):

Directive	Example	Description
%swiftir_setup	%swiftir_setup /opt/sdk	One-line SDK setup (recommended)
%swift_library_path	%swift_library_path /opt/lib	Add to LD_LIBRARY_PATH
%swift_module_path	%swift_module_path /opt/modules	Add Swift module search paths
%swift_env	%swift_env MY_VAR=/opt	Set environment variables
%swift_flags	%swift_flags -I/path -L/path	Add compiler flags
%swift_link	%swift_link MyLibrary	Link libraries
%swift_framework_path	%swift_framework_path /opt/fw	Add framework paths (macOS)
%swift_config	%swift_config	Display current configuration

Example usage:

// Set up a pre-compiled SDK
%swiftir_setup /opt/swiftir-deps

// Or configure paths individually
%swift_library_path /opt/mylib/lib
%swift_module_path /opt/mylib/swift-modules
%swift_link MyRuntime

// Verify configuration
%swift_config

// Now import and use
import MyRuntime

Compatibility

Component	Version
Swift	6.0+ (main-snapshot recommended)
Python	3.9-3.12
Jupyter	4.x / Notebook 7.x
macOS	12+ (Apple Silicon & Intel)
Linux	Ubuntu 22.04+

Documentation

• Google Colab Guide
• PythonKit Setup
• Changelog

License

Apache License 2.0

Acknowledgments

Originally created by Google as part of Swift for TensorFlow. Modernized in 2025 by Pedro Nahum.