Ergo Engine

Usage no npm install needed!

<script type="module">
  import accordprojectErgoEngine from 'https://cdn.skypack.dev/@accordproject/ergo-engine';


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This is the source code for the Ergo compiler. Ergo is the Accord Project language for Smart Legal Contracts.

The Ergo compiler is distributed as an npm package.

The Ergo compiler is written using the Coq proof assistant, with parsing and support code written in OCaml. It makes extensive use of the Q*cert compiler for code generation and type checking.

Both the Ergo language and its compiler are in early development phase. If you would like to build from source or to contribute, consult the DEVELOPERS file.

Try Ergo online

If you want to take a peek at Ergo without installing anything, check out the interactive REPL (read-eval-print-loop) for Ergo stand-alone, or the Accord Project Template Studio which illustrates Ergo in Accord Project templates.


The most recent Ergo documentation is in the [Ergo Language Guide][docergo].

Structure of the Code Repository

Top level repository (ergo), with sub packages. Each sub-package is published as an independent npm module using lerna:

  • ergo-cli : Command line interface for the Ergo compiler
  • ergo-compiler : Core classes for the Ergo compiler
  • ergo-engine : A Node.js VM based execution engine for Ergo
  • ergo-test : Cucumber based testing for Ergo


The easiest way to install Ergo is as a Node.js package. Once you have Node.js installed on your machine, you can get the Ergo compiler and command-line using the Node.js package manager by typing the following in a terminal:

$ npm install -g @accordproject/ergo-cli

This will install the Ergo command-line (ergo) and Read-Eval-Print-Loop (ergotop). Those will allow you to create, test and compile Ergo contracts. You can check your installed version by typing the following in a terminal:

$ ergo --version

Or to get command line help:

$ ergo --help
ergo <command>

  ergo draft       create a contract text from data
  ergo trigger     send a request to the contract
  ergo invoke      invoke a clause of the contract
  ergo initialize  initialize the state for a contract
  ergo compile     compile a contract

  --help         Show help                                             [boolean]
  --version      Show version number                                   [boolean]
  --verbose, -v                                                 [default: false]

Create contract text

To create a contract text from a contract:

$ ergo draft --template ./tests/volumediscount --data ./tests/volumediscount/data.json

Initialize a contract

To obtain the initial state of the contract:

$ ergo initialize --template ./tests/volumediscount --data ./tests/volumediscount/data.json
06:40:29 - info:

Send a request to a contract

To send a request to a contract:

$ ergo trigger --template ./tests/volumediscount --data ./tests/volumediscount/data.json --request ./tests/volumediscount/request.json --state ./tests/volumediscount/state.json
06:40:01 - info:
  "clause": "orgXaccordprojectXvolumediscountXVolumeDiscount",
  "request": {
    "$class": "org.accordproject.volumediscount.VolumeDiscountRequest",
    "netAnnualChargeVolume": 10.4
  "response": {
    "$class": "org.accordproject.volumediscount.VolumeDiscountResponse",
    "discountRate": 2.8,
    "transactionId": "13fa7cb6-03fc-4fd8-8e12-9a85ac8d5eb7",
    "timestamp": "2019-10-12T23:56:33.688Z"
  "state": {
    "$class": "org.accordproject.cicero.contract.AccordContractState",
    "stateId": "1"
  "emit": []

Invoke a clause

To invoke a specific clause of the contract:

$ ergo invoke --template ./tests/volumediscount --clauseName volumediscount --data ./tests/volumediscount/data.json --params ./tests/volumediscount/params.json --state ./tests/volumediscount/state.json

Compile a contract

To compile your first Ergo contract to JavaScript:

$ ergo compile ./tests/volumediscount/model/model.cto ./tests/volumediscount/logic/logic.ergo
Processing file: ./tests/volumediscount/logic.ergo -- compiled to: ./tests/volumediscount/logic.js

By default, Ergo compiles to JavaScript for execution. You can inspect the compiled JavaScript code in ./tests/volumediscount/logic.js

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Accord Project is an open source, non-profit, initiative working to transform contract management and contract automation by digitizing contracts. Accord Project operates under the umbrella of the Linux Foundation. The technical charter for the Accord Project can be found here.

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The Accord Project technology is being developed as open source. All the software packages are being actively maintained on GitHub and we encourage organizations and individuals to contribute requirements, documentation, issues, new templates, and code.

Find out what’s coming on our blog.

Join the Accord Project Technology Working Group Slack channel to get involved!

For code contributions, read our CONTRIBUTING guide and information for DEVELOPERS.


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