The Pact Programming Language
===
[](https://travis-ci.org/kadena-io/pact)
This is the source code repository for [Pact](http://kadena.io/pact), a language for developing
smart contracts to run on a [fast deterministic blockchain](http://kadena.io).
References
---
[Pact Homepage](http://kadena.io/pact)
[Pact Tutorials](http://pactlang.org)
[Pact Reference Docs](http://pact-language.readthedocs.io)
[Pact Whitepaper](http://kadena.io/docs/Kadena-PactWhitepaper.pdf)
Quick Start: Browser
---
The easiest way to try Pact is [in the browser](http://pact.kadena.io).
Quick Start: Atom
---
To start writing
smart contracts, the best way to go is to use the [Atom editor](https://atom.io) and install
`language-pact` using the [package manager](http://flight-manual.atom.io/using-atom/sections/atom-packages/).
Quick Start: Vim
---
If you are a [vim](https://vim.org) user, the [vim-pact](https://github.com/wsdjeg/vim-pact) plugin provides support for pact.
Installing Pact with Homebrew (OSX only)
---
You'll then need to install the Pact interpreter/REPL. On Mac, the easiest way to install `pact` is with Homebrew.
Make sure that Homebrew has been installed in your machine. Instructions for how to install it can be found [here](https://brew.sh/).
Once Homebrew is installed, run the following command to install `pact`:
```
brew install kadena-io/pact/pact
```
Installing Pact with Binary Distributions
---
Pact can also be installed by following the instructions below:
- Install [z3](https://github.com/Z3Prover/z3/wiki).
- Download the [prebuilt binaries](https://github.com/kadena-io/pact/releases) for your distribution. Or see [Building](#Building) for instructions on how to build Pact from the source code.
- Once you've downloaded the binary, make sure that it is marked as executable by running `chmod +x <executable-file>`.
- Put the binary somewhere in your PATH.
For installing `pact` on Linux distributions in the Arch family, refer to [this package on the AUR](https://aur.archlinux.org/packages/pact/).
Verifying Install
---
Test by issuing `pact` in a terminal. Try out some commands:
```
$ pact
pact> (+ 1 2)
3
pact> (+ "hello, " "world")
"hello, world"
```
There are [examples](examples/) in this source repository of working smart contracts which you can load into Atom to get started.
Quick Start: Pact REST API Server
---
Pact now features a full REST API HTTP server and SQLite database implementation, making
blockchain application development painless and easy. The Pact server simulates a single-node
blockchain environment, with the same API supported by the Kadena ScalableBFT blockchain.
To start the server, issue `pact --serve CONFIG` or `pact -s CONFIG`, where CONFIG is a valid [config.yaml](config.yaml).
#### REST API Docs
The REST API is documented at [http://pact-language.readthedocs.io/en/latest/pact-reference.html#rest-api](http://pact-language.readthedocs.io/en/latest/pact-reference.html#rest-api).
#### Related Projects
* The [pact-lang-api npm package](https://www.npmjs.com/package/pact-lang-api) provides a JavaScript library to aid interaction with the API.
* The [pact-todomvc](https://github.com/kadena-io/pact-todomvc) is a working demonstration.
#### Hosting static files.
The HTTP server will host any static files it finds in its working directory.
#### Config file format
The pact dev server (pact-serve) requires a configuration Yaml file (e.g. server.conf) to operate. The documentation for it is:
```
➜ pact git:(feat/dev-server) pact --serve --help
Config file is YAML format with the following properties:
port - HTTP server port
persistDir - Directory for database files.
If ommitted, runs in-memory only.
logDir - Directory for HTTP logs
pragmas - SQLite pragmas to use with persistence DBs
verbose - [True|False] Provide extra logging information
```
#### Replay from disk.
When running pact-serve with persistence enabled, the server automatically replays from the database
`commands.sqlite` in the persist dir. To prevent replay, simply delete this file before starting the server.
Building Pact
---
### Building with Stack
[Install stack](https://docs.haskellstack.org/en/stable/README/#how-to-install)
Issue `stack build` on the command line.
Use `stack install` to install on the command line and for Atom, ensuring that `$HOME/.local/bin` is on your PATH.
### Building with Nix
The fastest way to build and run pact is to use the Nix package manager
which has binary caching capabilities that allow you to download pre-built
binaries for everything needed by pact. For detailed instructions see [our
wiki](https://github.com/kadena-io/pact/wiki/Building-Kadena-Projects).
When the build is finished, you can run pact with the following command:
```bash
./result/ghc/pact/bin/pact
```
#### Incremental Builds
Building with `nix-build` does a full rebuild every time, which is usually not
what you want when developing. To do incremental builds, you need to enter a nix
shell. To do that use the `nix-shell` command.
This puts you in a shell that has all the necessary dependencies installed. Once
inside this shell you can build as normal with cabal using `cabal build` or
`cabal new-build`.
You can also build with stack inside this shell as follows:
```
$ stack --stack-yaml stack-nix.yaml build
```
#### Hoogle Documentation
Nix has out-of-the-box Hoogle integration. It allows you to run a local
Hoogle server with docs for all of the project dependencies. This is really
nice for two reasons:
1. You know you're getting correct docs for the exact versions of the packages
you are depending on.
2. You don't have to have an internet connection to access them.
To start the hoogle server, run this command from the project root directory.
```
nix-shell --run 'hoogle server --local'
```
This runs hoogle locally on port 8080. Running it this way, however, does not
include haddocks for the pact (or whatever tho local project is). It only
includes docs for the dependencies. To fix this, use the following command
instead:
```
nix-shell -p 'with import ./. {}; ghc.ghcWithHoogle (p: [p.pact])' --run 'hoogle server --local'
```
To use the above command for other projects that use the [`.project`
function](https://github.com/kadena-io/pact/blob/master/default.nix#L12)
replace `[p.pact]` with a list of all the locally defined projects to include.
For example: `[p.backend p.common p.frontend]` for a project that has those
three separate local packages.
License
---
This code is distributed under the terms of the BSD3 license. See [LICENSE](LICENSE) for details.