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Jun 7, 2021

The Unison language

Build Status

Unison is a new programming language, currently under active development. It's a modern, statically-typed purely functional language, similar to Haskell, but with the ability to describe entire distributed systems with a single program. Here's an example of a distributed map-reduce implementation:

-- comments start with `--`
mapReduce loc fn ifEmpty reduce data = match split data with
  Empty          -> ifEmpty
  One a          -> fn a
  Two left right ->
    fl = at loc '(mapReduce loc fn ifEmpty reduce !left)
    fr = at loc '(mapReduce loc fn ifEmpty reduce !right)
    reduce !fl !fr

This function can be either simulated locally (possibly with faults injected for testing purposes), or run atop a distributed pool of compute.

If you'd like to learn more about the project, this Strange Loop talk is a good introduction. You can also follow along with project website or you can also say hello or lurk in the Slack chat.

We are currently alpha testing Unison. If you'd like to participate in alpha testing, you can go to the docs site to get started.

Building using Stack

If these instructions don't work for you or are incomplete, please file an issue.

The build uses Stack. If you don't already have it installed, follow the install instructions for your platform. (Hint: brew update && brew install stack)

$ git clone
$ cd unison
$ stack --version # we'll want to know this version if you run into trouble
$ stack build && stack exec tests && stack exec unison

To run a local codebase-ui while building from source, you can use the / script. It will download the latest release of the codebase-ui and put it in the expected location for the unison executable created by stack build. When you start unison, you'll see a url where the codebase-ui is running.

See development.markdown for a list of build commands you'll likely use during development.

Codebase Server

When ucm starts it starts a Codebase web server that is used by the Codebase UI. It selects a random port and a unique token that must be used when starting the UI to correctly connect to the server.

The port, host and token can all be configured by providing environment variables when starting ucm: UCM_PORT, UCM_HOST, and UCM_TOKEN.