Blog on The Coalton Programming Language

Introducing mine, a Coalton and Common Lisp IDE

Fri, 24 Apr 2026 00:00:00 +0000

mine is a brand new IDE for Coalton and Common Lisp, built from the ground up with one purpose: To make Coalton and Common Lisp easier and more accessible to the programming world.

TL;DR? Go to mine's homepage with downloads for Windows/macOS/Linux.

mine is a complete, single-download application that comes with everything needed to experience the interactive and incremental development programming workflow, including hot-reloading and on-the-fly debugging, that Lisp programmers often refer to as the differentiating feature of the ecosystem. After installing, one can immediately open a file, program some Coalton or Lisp, and beam code to the REPL. On the same token, it has many of the advanced features you’d expect in a professional IDE:

A Preview of Coalton 0.2

Thu, 12 Mar 2026 00:00:00 +0000

By Robert Smith

Coalton is a statically typed functional programming language that lives inside Common Lisp. It has had an exciting few years. It is being used for industrial purposes, being put to its limits as a production language to build good, reliable, efficient, and robust products. Happily, with Coalton, many products shipped with tremendous success. But as we built these products, we noticed gaps in the language. As such, we’re setting the stage for the next tranche of Coalton work, and we’re going to preview some of these improvements here, including how Coalton can prove $\sqrt{2+\sqrt{3}} = \sqrt{2}(\sqrt{3}+1)/2$ exactly.

Using Common Lisp Libraries from Coalton

Tue, 12 Aug 2025 00:00:00 +0000

By Robert Smith

We discuss how we can make an efficient, type-safe interface to existing libraries written in Common Lisp so that they can be used in Coalton code.

One of Coalton’s headline features is that it’s embedded in Common Lisp, and allows the use of Common Lisp code via the lisp operator. However, it’s not immediately obvious how one can use Common Lisp when Coalton is strongly typed. How do we do it?

Using Coalton to Implement a Quantum Compiler

Tue, 06 Sep 2022 00:00:00 +0000

By Elias Lawson-Fox, Aidan Nyquist, and Robert Smith

Updated July 1, 2025 by Robert Smith.

Introduction: Coalton and the quilc compiler

Quilc is a state-of-the-art optimizing compiler for quantum computers written in Common Lisp. It is capable of taking arbitrary quantum programs written in Quil, and compiling and optimizing them into code that conforms to the majority of quantum computing architectures that exist today.

Numbers in a Nutshell, an Update

Sat, 27 Aug 2022 00:00:00 +0000

By Robert Smith

We discuss numbers and math in Coalton, as they are so far. Coalton is under active development, so this blog post may go out of date in due time.

Introduction

Coalton is statically typed, which presents some challenges in how we work with numbers, both syntactically and semantically. For instance, consider the following Common Lisp code:

One Reason Typeclasses Are Useful

Sun, 12 Dec 2021 00:00:00 +0000

By Robert Smith

In this post, we explore one way that typeclasses are useful. We do so by first painting ourselves into a corner while building a toy Common Lisp program, and then seeing how Coalton’s typeclasses can ameliorate the issues.

A Graphics Library

Let’s write a graphics library. Or, a tad less ambitiously, let’s write some routines for performing transformations on 2D points, which might serve as the foundation of a graphics library. We’ll be interested in:

AoC 2021 Coalton Contest

Mon, 29 Nov 2021 00:00:00 +0000

By Robert Smith

Update: The prizes have been matched 1:1 by a donor who wishes to remain anonymous!

Introduction

Last September we announced Coalton, a statically typed language that is “just” another Common Lisp DSL. To our great surprise, there was a lot of excitement and fanfare, which made the development team feel quite honored and proud. It even made the top of Hacker News!

Unsurprisingly, as is the case with many open-source projects, that fanfare lead to little “conversion”; only a few people actually gave Coalton a shot and provided feedback. We are immensely thankful to those who did! The good news is that it lead to some good discussion, great PRs, and fantastic internship applications from a wonderful and diverse group of people. We won’t be able to accept everyone but I’m pleased that there’s interest in helping build out the next generation of quantum computational tools using “alien technology”. :)

Introducing Coalton: How to Have Our (Typed) Cake and (Safely) Eat It Too, in Common Lisp

Fri, 10 Sep 2021 00:00:00 +0000

By Robert Smith, Elias Lawson-Fox, Cole Scott

Updated July 1, 2025 by Robert Smith.

Introduction

Coalton is a statically typed functional programming language built with Common Lisp. We can load it like a normal Lisp library.

CL-USER> (asdf:load-system "coalton")
CL-USER> (in-package #:coalton-user)
COALTON-USER>

This is Coalton computing Fibonacci numbers by exponentiating functions (not numbers!):

(coalton-toplevel
  (declare function-power (Integer -> (:t -> :t) -> (:t -> :t)))
  (define (function-power n f)
    (if (<= n 0)
        id
        (compose f (function-power (1- n) f))))
                
  (declare fib-step ((Tuple Integer Integer) -> (Tuple Integer Integer)))
  (define (fib-step (Tuple a b))
    (Tuple b (+ a b)))
                
  (declare fib (Integer -> Integer))
  (define (fib n)
    (fst ((function-power n fib-step) (Tuple 0 1)))))

This is Coalton greeting you by making native use of Common Lisp functions:

Blog on The Coalton Programming Language

Introducing mine, a Coalton and Common Lisp IDE

A Preview of Coalton 0.2

Using Common Lisp Libraries from Coalton

Table Of Contents

Using Coalton to Implement a Quantum Compiler

Table Of Contents

Introduction: Coalton and the quilc compiler

Numbers in a Nutshell, an Update

Table Of Contents

Introduction

One Reason Typeclasses Are Useful

A Graphics Library

AoC 2021 Coalton Contest

Introduction

Introducing Coalton: How to Have Our (Typed) Cake and (Safely) Eat It Too, in Common Lisp

Introduction