MVS-Calculus

The mvs-calculus is a small experimental language, centered around the concept of mutable value semantics.

Unrestricted mutation of shared state is a source of many well-known problems. The predominant safe solutions are pure functional programming, which simply bans mutation. Mutable value semantics is a different approach that bans sharing instead of mutation, thereby supporting part-wise in-place mutation and local reasoning.

Installation

This project is written in Swift and distributed in the form of a package, built with Swift Package Manager.

You will need to install LLVM 11.0. Use your favorite package manager (e.g., port on macOS or apt on Ubuntu) and make sure llvm-config is in your PATH. Then, create a pkgconfig file for your specific installation. The maintainers of LLVMSwift were kind enough to provide a script:

swift package resolve
swift .build/checkouts/LLVMSwift/utils/make-pkgconfig.swift

On Ubuntu, you will also need libc++ to link your code with LLVM:

apt-get install libc++-dev
apt-get install libc++abi-dev

Once LLVM is installed and configured, compile the compiler and the runtime library with the following commands:

swift build -c release
c++ -std=c++14 -c Runtime/runtime.cc -o .build/release/runtime.o

You may compile the runtime with the flag DEBUG for debugging purposes. Calls to the runtime's API will be logged as programs are executed.

Usage

The mvs executable compiles programs into object files, which you can link with clang or ld. Pass the flag -O to compile with optimizations.

.build/release/mvs -O Examples/Factorial.mvs
c++ .build/release/runtime.o Examples/Factorial.o -o Examples/Factorial
Examples/Factorial
# Prints 720

Run mvs --help for an overview of the compiler's options.

Publications

• Dimitri Racordon, Denys Shabalin, Daniel Zheng, Dave Abrahams and Brennan Saeta. Implementation Strategies for Mutable Value Semantics, Journal of Object Technology (preprint)