virgil: A Fast and Lightweight Systems Programming Language

def main() {
    System.puts("Virgil is fast and lightweight!\n");
}

Virgil is a programming language designed for building lightweight high-performance systems. Its design blends functional and object-oriented programming paradigms for expressiveness and performance. Virgil's compiler produces optimized, standalone native executables, WebAssembly modules, or JARs for the JVM. For quick turnaround in testing and debugging, programs can also be run directly on a built-in interpreter. It is well-suited to writing small and fast programs with little or no dependencies, which makes it ideal for the lowest level of software systems. On native targets, it includes features that allow building systems that talk directly to kernels, dynamically generate machine code, implement garbage collection, etc. It is currently being used for virtual machine and programming language research, in particular the development of a next-generation WebAssembly virtual machine, Wizard.

This repository includes the entire compiler, runtime system, some libraries, tests, documentation and supporting code for Virgil's various compilation targets.

Language Design

Virgil focuses on balancing these main features in a statically-typed language:

• Classes - for basic object-oriented programming
• Functions - for small-scale reuse of functionality
• Tuples - for efficient aggregation and uniform treatment of multi-argument functions
• Type parameters - for powerful and clean abstraction over types
• Algebraic data types - for easy building and matching of data structures

For more, read this paper. Or see the tutorial. Or read up on libraries.

Supported Targets

Virgil can compile to native binaries for Linux or Darwin, to jar files for the JVM, or to WebAssembly modules. Linux binaries can run successfully under Windows using Window's Linux system call layer. The compiler is naturally a cross-compiler, able to compile from any supported platform to any other supported platform, so you need only be able to run on one of these platforms in order to target any of the others.

• x86-darwin : 32-bit Darwin kernels (MacOS)
• x86-64-darwin : 64-bit Darwin kernels (MacOS)
• x86-linux : 32-bit Linux kernels
• x86-64-linux : 64-bit Linux kernels
• jar : JAR files for the Java Virtual Machine
• wasm : WebAssembly module for any Wasm engine

Implementation

Virgil is fully self-hosted: its entire compiler and runtime system is implemented in Virgil. It was originally designed as a language for embedded systems, particularly microcontrollers, but now supports more mainstream targets. The compiler includes sophisticated whole-program optimizations that achieve great performance and small binaries. Native binaries compiled from your programs can be as small as a few hundred bytes in size and consume just kilobytes of memory at runtime. You can learn more in the Implementation Guide.

Documentation

The most up-to-date documentation is, as always, this repository! Learn how to get started using Virgil and browse the tutorial, where many example programs exist.

Editor Support

A Visual Studio Code extension with syntax highlighting, semantic highlighting, and debugging lives in the virgil-vscode repository.

Research Papers

Six research papers have been published on Virgil.

• Bradley Wei Jie Teo and Ben L. Titzer. Unboxing Virgil ADTs for Fun and Profit. In Proceedings of the Workshop Dedicated to Jens Palsberg on Occasion of of His 60th Birthday (JENSFEST 24). Pasadena, CA. October 2024.

• Ben L. Titzer. Harmonizing Classes, Functions, Tuples and Type Parameters in Virgil III [pdf]. In Proceedings of the ACM Conference on Programming Language Design and Implementation (PLDI '13). San Diego, CA. June 2013.

• Stephen Kou and Jens Palsberg. From OO to FPGA: Fitting round objects into square hardware? [pdf] In Proceedings of the ACM Conference on Object-Oriented Programming Systems, Languages and Applications (OOPSLA '10). Reno, Nevada, 2010.

• Ben L. Titzer and Jens Palsberg. Vertical Object Layout and Compression for Fixed Heaps. In Semantics and Algebra Specification. Pp. 376-408. 2009.

• Ben L. Titzer and Jens Palsberg. Vertical Object Layout and Compression for Fixed Heaps [pdf]. In Proceedings of the International Conference on Compilers, Architecture, and Synthesis for Embedded Systems (CASES ’07). Salzburg, Austria. October 2007.

• Ben L. Titzer. Virgil: Objects on the Head of a Pin [pdf]. In Proceedings of the 21 st Annual Conference on Object-Oriented Systems, Languages, and Applications (OOPSLA '06). October 2006.

License

Licensed under the Apache License, Version 2.0. (rt/LICENSE or https://www.apache.org/licenses/LICENSE-2.0)