Why We Open-Sourced Our Blockchain’s Smart Contract Language

Vivienne Chen
3 min readMay 4, 2018


Back in November 2016, Kadena open-sourced our smart contract language, Pact™. Open-sourcing is all about empowering users, and that’s also what motivated us to make Pact in the first place––to empower people to enact meaningful events on a blockchain, safely and quickly.

We believe open-source initiatives provide transparency and benefits to everyone, including:


If you are a developer writing smart contracts, an open-source language means you’re not dependent on out-of-date docs to educate you since you can always look at the code, and if there’s a problem you want to fix now, you simply fork and fix it.

Business users

If you are a business user, open-source means you can develop your business logic in Pact to run on a fast private blockchain like ScalableBFT, knowing that your code is your own and it’s not encumbered by NDAs or licenses.

And soon, users will be able to run projects in Pact on Chainweb, Kadena’s public blockchain, running on a fully distributed open network with the power of a scalable, proof of work protocol at its consensus layer.


Open-source also empowers us at Kadena, by leveraging the amazing ecosystem for software development. Pact is hosted on Github, is automatically built on every commit by Travis-CI, which we further leverage to make builds for multiple OSs on our downloads page. Our docs are hosted on readthedocs.org.

All of these amazing resources work together seamlessly and for free — if your project is open-source. It’s an excellent example of alternate incentivization schemes to encourage contributions to the public. And of course, we couldn’t even develop the technology without the peerless open-source language Haskell and all of the unbelievable community libraries available for it.

Current Pact Features

Headline features of Pact are:

Easy-to-use database metaphor

Pact puts the power of a flexible, fast key-value versioned database in your hands, making it easy to quickly model assets or other entities.

Simple module system

Pact allows for great factoring of smart-contract solutions. Modules hold related functions and constants, and also have the ability to “guard” tables. Re-using and factoring code is safe and easy.

Durable, safe code

Pact code is Turing-incomplete — unbounded looping is impossible, and recursion is detected when smart-contract modules are loaded into the blockchain. This also allows any referenced code to be inlined at load time, making for blazing performance, but also insuring that your code will not be harmed if an imported module is later re-defined.

Public-key authorization schemes, with external verification

Inspired by Bitcoin scripts, Pact is designed with access control in mind from the ground-up. The concept of keysets ensures that any resource can be controlled by one or more public keys. Modules, tables and even rows in the database can all be governed by separate keyset rules. The key verification itself is handled by the blockchain running the contract: a developer never need worry about faulty crypto.

Oracles, escrow and multi-phase transactions with “pacts”

Pacts are special multi-step functions in Pact that make authoring oracle processes and escrow transactions easy, trustless and safe. Pacts can “own” money to safely lock funds during the course of a multi-step transaction, and make workflow automation simple and safe. Our private blockchain, ScalableBFT, also allows for confidential message channels, in which pacts serialize execution between parties to ensure referential transparency and correctness.

Go forth and transact!

Finally there’s an alternative for creating smart contracts. We’re very excited to see what developers and business users can create with this technology. Once you’re ready to run them on the fastest blockchain, send us a note.

About Pact

Pact is an innovative way to write smart contracts on a blockchain, with a level of assurance not possible with other smart-contract languages. Pact is an expressive, easy-to-learn, and productive language to code in, with excellent tooling. Try it today, download a build or build and hack on it yourself.

Portions of this post were originally published by Stuart Popejoy, Kadena founder, in 2016 and have been updated and reprinted with permission here.