Some Random Thoughts on Clstrfsck

Advent of Code 2025 Day 10 Redux— Kotlin

Sat, 27 Dec 2025 17:00:00 +0000

Please see the original day 10 post for the Rust and good_lp solution I initially coded up. For other Kotlin solutions see the cheesy day 12 post.

The Code

This is an implementation of the ideas in a post by u/tenthmascot on Reddit.

The Reddit post linked above has a good description of the algorithm. I won’t repeat it here as it’s not my work, but the post’s title “Bifurcate your way to victory!” sums it up quite well.

Advent of Code 2025 Day 12— Kotlin

Fri, 12 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

Kotlin

Concise. Multiplatform. Fun.

— kotlinlang.org

Kotlin is a great language. It’s the language of choice for Android development, and for folks working in the JVM space, it has access to all of the vast array of Java frameworks and libraries. The standard library is large and well thought out.

Visual Studio Code support is meh. Most folks use IntelliJ IDEA.

The Code

I first “solved” this using a spreadsheet. I figured there would be a bunch of cases that could be trivially excluded, and a bunch of cases that could be trivially included, and I would just have to work out how to address what was left over. It turns out that the “difficult” problem set was quite small…

Advent of Code 2025 Day 11— Haskell

Thu, 11 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

Why Haskell?

A new paradigm

Composition and predictability

Declarative

Performance

Abstraction

Excellent tooling

— haskell.org (abridged)

I started with Swift, but I couldn’t resist rewriting the solution in Haskell. This problem is practically tailor-made to showcase the benefits of non-strict evaluation.

Visual Studio Code support for Haskell is excellent.

The Code

We define a map memo, populated with all possible nodes and flag values. The values in memo are unevaluated calls to count. count is then defined to look up the values it needs in memo.

Advent of Code 2025 Day 10— Rust

Wed, 10 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

Rust

A language empowering everyone to build reliable and efficient software.

— rust-lang.org

A somewhat understated soundbite briefly covering Rust’s impact on the software industry.

Rust is currently a highly favored systems programming language, a position it has earned to a significant degree. In my view, its significant popularity can sometimes lead to its selection in scenarios where other languages might be a more productive choice. Perhaps similar but orthogonal to the position that Python enjoys.

Advent of Code 2025 Day 9— Python

Tue, 09 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

Python is a programming language that lets you work quickly and integrate systems more effectively.

— python.org

I estimate that 97.23% of all Advent of Code solutions are written in Python. It is a super legible, super productive language with enormous libraries that everyone uses. You’ve probably used it yourself. It’s pretty much the standard scripting language in use today. It’s really easy to get stuff done. The downside is that in most cases, that stuff will run more slowly than in a compiled language.

Advent of Code 2025 Day 8— Go

Mon, 08 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

Build simple, secure, scalable systems with Go

An open-source programming language supported by Google

Easy to learn and great for teams

Built-in concurrency and a robust standard library

Large ecosystem of partners, communities, and tools

— go.dev

In my view, Go (aka Golang if you want to google something), is a great language for folks that value getting stuff done. The language designers have made a language that has deliberately kept the core set of functionality and keywords small and opinionated. For example, there are no public or private or even protected keywords in Go. Public declarations start with a capital letter (eg PublicFunction()), and non-public declarations do not (eg nonPublicFunction()).

Advent of Code 2025 Day 7— Common Lisp

Sun, 07 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

Common Lisp is intended to meet these goals:

Commonality

Portability

Consistency

Expressiveness

Compatibility

Efficiency

Power

Stability

— Common Lisp The Language 2e, Guy L. Steele Jr. (abridged)

I’ve included the list of design goals from the introduction of Common Lisp The Language, Second Edition. There is a greater explanation of each point in the introduction, spanning several pages which I did not want to reproduce here.

Advent of Code 2025 Day 6— C++

Sat, 06 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

C++ was designed with systems programming and embedded, resource-constrained software and large systems in mind, with performance, efficiency, and flexibility of use as its design highlights. C++ has also been found useful in many other contexts, with key strengths being software infrastructure and resource-constrained applications, including desktop applications, video games, servers (e.g., e-commerce, web search, or databases), and performance-critical applications (e.g., telephone switches or space probes).

Advent of Code 2025 Day 5— Crystal

Fri, 05 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

Crystal is a general-purpose, object-oriented programming language. With syntax inspired by Ruby, it’s a compiled language with static type-checking. Types are resolved by an advanced type inference algorithm.

— crystal-lang.org

Crystal uses LLVM to compile to native code, without the verbose syntax usually associated with systems languages.

Visual Studio Code support for Crystal is available, but not as complete as some other languages. I understand from googling around that LSP support is more complex because of the syntactic flexibility.

Advent of Code 2025 Day 4— Racket

Thu, 04 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

Mature: Racket is a mature and stable product. From the beginning, it has supported cross-platform graphical programming (Windows, macOS, Linux).

Practical: Racket includes a rich set of libraries, covering the full range from web server apps to mathematics and scientific simulation software.

Extensible: In Racket, programmers define their own loops with powerful macros. Indeed, these macros are so powerful that programmers make entire domain-specific languages as libraries. No tools, no Makefiles required.

Advent of Code 2025 Day 3— D

Wed, 03 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

D is a general-purpose programming language with static typing, systems-level access, and C-like syntax. With the D Programming Language, write fast, read fast, and run fast.

— dlang.org

Unfortunately most of the systems programming languages I’ve used in AoC 2025 appear to have lost the systems-programming race to Rust and maybe Go. That’s something of a shame, as D seems like a worthy modern alternative to C and C++.

Advent of Code 2025 Day 2— Julia

Tue, 02 Dec 2025 05:00:00 +0000

The Julia Github repo has this to say about the language:

Julia is a high-level, high-performance dynamic language for technical computing.

— github.com/JuliaLang/julia

Like many languages focussed on numerical computing, Julia has 1-based array indexing. I don’t think this is a major issue, but I imagine it would be something that would occasionaly trip up folks coming from 0-based languages while they adjust.

Visual Studio Code support for Julia is excellent.

Advent of Code 2025 Day 1— Nim

Mon, 01 Dec 2025 05:00:00 +0000

Marketing Pitch and Impressions

The Nim website describes the language like this:

Nim is a statically typed compiled systems programming language. It combines successful concepts from mature languages like Python, Ada and Modula.

— nim-lang.org

There are a few additional interesting points worth noting:

Compiles to C, C++, or JavaScript, presumably making targeting new architectures easier.
Automatic memory management via ARC or ORC, where ORC is ARC with cycles.
Compile-time Function Execution (CTFE), which permits compile-time computation and AST manipulation.
Syntax is similar to Python, using indentation for code blocks.

I quite like the ideas behind Nim. It has a decent library, automatic memory management, modern tooling and compiles to native code. The syntax is easy to read and pleasant to work with.