Coinward / simplicity

Simplicity is a blockchain programming language designed as an alternative to Bitcoin script.

Simplicity

Simplicity is a blockchain programming language designed as an alternative to Bitcoin script.

The language and implementation is still under development.

Contents

This project contains

• A Haskell implementation of Simplicity's language semantics, type inference engine, serialization functions, and some example Simplicity code.
• A Coq implementation of Simplicity's formal denotational and operational semantics.

Build

Building with Nix

Software artifacts can be built using Nix.

• To build the Haskell project, run nix-build -A haskell.
• To use the Haskell project, try nix-shell -p "(import ./default.nix {}).haskellPackages.ghcWithPackages (pkgs: [pkgs.Simplicity])".
• To build the Coq project, run nix-build -A coq.

Building without Nix

To build the Coq project, we first need to build the VST dependency.

1. Download and extract the lastest VST from https://github.com/PrincetonUniversity/VST/archive/v2.4.tar.gz.
2. Build the VST project by running make in the extracted directory. If you are in a rush it is sufficent to run make sha/functional_prog.vo. (Tip: if you have a newer version of Coq, you can try setting the environment variable IGNORECOQVERSION=true.)
3. Install the VST project into your user's .local/share (or XDG_DATA_HOME) directory by running
   1. mkdir -p ${XDG_DATA_HOME:-$HOME/.local/share}/coq/VST
   2. cp -r msl sepcomp veric floyd ${XDG_DATA_HOME:-$HOME/.local/share}/coq/VST
   3. cp -r compcert sha ${XDG_DATA_HOME:-$HOME/.local/share}/coq

Now we can build the Simplicity project.

1. Enter the Coq directory.
2. Execute coq_makefile -f _CoqProject -o CoqMakefile.
3. Build the project by executing make -f CoqMakefile.

Documentation

Detailed documentation can be found in the Simplicity-TR.tm TeXmacs file. A recent PDF version can be found in the pdf branch.

Further Resources

• Our paper that originally introduced Simplicity. Some of the finer details are out of date, but it is still a good introduction.
• BPASE 2018 presentation of the above paper (slides).
• Scale by the Bay 2018 presentation that illustrates formal verification of Simplicity in Agda (slides).

Contact

Interested parties are welcome to join the Simplicity mailing list. Issues and pull-requests can be made through GitHub's interface.