Unison Syntax: A Comprehensive Guide

Are you tired of wading through cryptic symbols and confusing syntax just to accomplish simple coding tasks? Do you wish there was a programming language that was easy to learn, easy to use, and easy to read? Look no further than Unison!

Unison is a groundbreaking programming language that combines the rigorous functional programming of Haskell with a revolutionary new approach to syntax. In this comprehensive guide, we'll explore the ins and outs of Unison syntax, so you can start coding like a pro in no time!

Understanding Unison Basics

At its core, Unison is a functional programming language that utilizes immutable values and pure functions. This means that you don't have to worry about side effects or unexpected changes to your code – everything in Unison is predictable and reliable.

But what sets Unison apart is its syntax. Unlike traditional programming languages, Unison's syntax is designed to be human-readable and intuitive. Instead of using complex symbols and brackets, Unison uses natural language terms and indentation to convey meaning.


Let's start with functions. In Unison, a function is defined using the -> operator. Here's an example:

length : List a -> Nat

In this example, we're defining a length function that takes a list of a values and returns a Nat value. Notice how the syntax is clean and concise – no need to clutter your code with unnecessary symbols!


Unison also uses natural language terms to define types. For instance, here's how you might define a custom data type in Unison:

data Color = Red | Green | Blue

In this example, we're defining a Color data type that can take on one of three values: Red, Green, or Blue. Again, the syntax is simple and straightforward.

Pattern Matching

Unison also supports pattern matching, which allows you to match a function's arguments with specific patterns. Here's an example:

square : Nat -> Nat
square 0 = 0
square n = n * n

In this example, we're defining a square function that takes a Nat value and returns its square. Notice how we're able to define two separate patterns for the function's argument – one for when the argument is 0, and one for all other values.

Advanced Unison Syntax

Now that we've covered the basics of Unison syntax, let's dive into some of the more advanced features.

Type Aliases

Unison supports type aliases, which allow you to define shorter names for more complex types. Here's an example:

type Name = Text

In this example, we're defining a Name type alias that is equivalent to the Text type. This can be useful for simplifying your code and making it more readable.


Unison also supports modules, which allow you to organize your code into logical units. Here's an example:

module Math where
  square : Nat -> Nat
  square n = n * n

In this example, we're defining a Math module that contains a square function. This can be useful for separating different parts of your code and keeping everything organized.


Finally, Unison supports records, which allow you to define structured data types with named fields. Here's an example:

type Person = { name: Text, age: Nat }

In this example, we're defining a Person record type with two fields – name and age. This can be useful for representing complex data structures in a more readable and intuitive way.

Tips for Working with Unison Syntax

While Unison's syntax is designed to be easy to read and understand, there are still a few tips and tricks that can help you write cleaner and more efficient code.

Use Comments

As with any programming language, comments can be a lifesaver when it comes to understanding your code. Unison supports both single-line and multi-line comments, so don't be afraid to use them liberally!

Indentation Matters

One of the keys to Unison's syntax is its use of indentation to denote different blocks of code. Make sure to stay consistent with your indentation levels, or you'll quickly find yourself lost in a sea of mismatched brackets.

Practice Patience

Unison's syntax may take some getting used to, especially if you're coming from a more traditional programming language. Don't be discouraged if it takes a little while to get the hang of things – with practice, you'll soon be coding like a pro!


Unison is a revolutionary programming language that combines the power of functional programming with a clean, intuitive syntax. Whether you're a seasoned programmer or a beginner just getting started, Unison is a language that's easy to learn and easy to use.

We hope this comprehensive guide has given you a better understanding of Unison syntax and how it can be used to create clean, efficient code. So what are you waiting for? Start exploring Unison today, and see what this amazing language can do for you!

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Written by AI researcher, Haskell Ruska, PhD (haskellr@mit.edu). Scientific Journal of AI 2023, Peer Reviewed