⏳ Three-minute quickstart guide

This short guide will have you downloading and installing Unison and running your first program. There isn't much exposition here and the focus is on getting you up and running as quickly as possible.

More in-depth guides follow this one.

Step 1: Install Unison

If you haven't already, please join the#generaland#troubleshootingchannels on Discord.

We are really hoping that if you are trying out Unison you'll come talk to us, ask questions, and report bugs! We want you to have a welcoming and positive experience when getting started! 😊

Installation options

The current release is for Mac OS X, 64-bit Linux, and Windows users!

Option 1: Installing or updating using Homebrew
Option 1: Installing or updating using Homebrew

Firstinstall homebrewif you haven’t already.

Then from the command line enter these commands (or better yet, paste them into your console):

brew tap unisonweb/unison
brew install unison-language

This will install the Unison codebase manager executable ucm. If you’re upgrading from a previous version, just dobrew upgrade unison-language.

Note: if you get prompted for a GitHub username and password at this point, make sure you spelled unisonweb/unison correctly.

Option 2: Install manually for Mac and Linux users
Option 2: Install manually for Mac and Linux users


mkdir -p unisonlanguage && cd unisonlanguage
curl -L https://github.com/unisonweb/unison/releases/latest/download/ucm-linux.tar.gz \
	| tar -xz


mkdir -p unisonlanguage && cd unisonlanguage
curl -L https://github.com/unisonweb/unison/releases/latest/download/ucm-macos.tar.gz \
  | tar -xz
Option 3: Install manually for Windows users
Option 3: Install manually for Windows users
  1. Set your default terminal application to “Windows Terminal” for best results. Search for “Terminal” in Settings, or followthis how-to.
  2. DownloadUCMand extract it to a location of your choosing.
  3. Runucm.exe🎉
Option 4: Nix installation
Option 4: Nix installation
Head tohttps://github.com/ceedubs/unison-nix/#usageand follow the instructions in the readme there.

Unison Language Server installation

Unison has a Language Server Protocol (LSP) integration!Instructions for downloading and setting up the Unison Language Server are available here.

Step 2: Create your Unison codebase

Runucmto initialize a Unison codebase in$HOME/.unison.This is where Unison will store function definitions, types, namespaces, and so on.

Step 3: Create the quickstart project

A Unison codebase is subdivided into manyprojects.Unison projects represent the various libraries, applications, or programs that you might be working on. From the root of your codebase, represented with.,use theproject.createcommand to make a new quickstart project. It will create amainbranch for you to work in.

.> project.create quickstart

You'll see the UCM download thebasestandard library into alibnamespace. Namespaces help give structure to Unison code because a Unison codebase isn't saved to the file system. You can think of this as our analog to a directory structure. Namespace segments are separated with the.character. A project's dependencies are located in a special namespace calledlib.The code for our quickstart project will be simple, so we only need thebaselibrary in scope. Check that thebaselibrary has been downloaded by runningls lib.basein the UCM.

quickstart/main> ls lib.base

Run your first program

Head to the text editor of your choosing and create a new file calledscratch.uin the directory where you launcheducm(so if you launcheducmfrom~/myUnisonCode,you'd create~/myUnisonCode/scratch.u).Add the following code to the file:

myTerm = List.map (x -> x * 10) [1,2,3,4,5,6]
> myTerm

The first line is defining a Unison term calledmyTerm.This one multiplies every element in a list by10,using thelib.base.data.List.mapfunction.

The second, beginning with>,is awatch expression.

Theucmmonitors all the unison source files in the current directory for changes and evaluates any watch expressions:


  I found and typechecked these definitions in ~/myUnisonCode/scratch.u. If you do an `add` or
  `update`, here's how your codebase would change:

    ⍟ These new definitions are ok to `add`:

      myTerm : [Nat]

  Now evaluating any watch expressions (lines starting with `>`)... Ctrl+C cancels.

    2 | > myTerm
          [10, 20, 30, 40, 50, 60]

Congratulations, you ran your first Unison program!

We want to hear from you!

If you have any trouble with the process, or have ideas about how to improve this document,come talk to us in the#troubleshootingDiscord channel!