Carlo Hämäläinen

I’m currently reading Adam Becker’s More Everything Forever (2025), a physicist’s tour of the ideologies of Silicon Valley: the Singularity, AI doom, effective altruism, longtermism, Mars settlement.

Live demo: https://ghc-vis-ds.hamalainen.dev Source: https://github.com/carlohamalainen/ghc-vis-ds Discourse: https://discourse.haskell.org/t/ghc-vis-ds-a-modern-port-of-ghc-vis-with-a-datastar-frontend/14520 A live view of the GHC heap in your browser: i…

Back in the old days, people used to leave comments on blogs.

My current setup: Small townhouse in Brisbane. 3.9kW solar array (ugh small roof).

Full source code and talk: https://github.com/carlohamalainen/bfpg-2026-05-12-datastar-haskell-sdk

The Question Link to heading When we have many data structures that contain the same large value, does GHC preserve sharing to save memory?

Performance surprises are everywhere - even in the simplest code 🚀 At my old bank job, I discovered something eye-opening: for some requests, our code spent more time logging than doing the actual mathematical calculations and data loading combined.

Software estimation is hard.

Have you ever typed $ sudo chmod -R 400 * and then wondered which directory you were in?

Setting up TLS with Caddy on a Digital Ocean droplet is so easy with the Caddy DNS plugin.

The goal is to deploy automatic TLS certificates using cert-manager, with certificates supplied by Let’s Encrypt.

I migrated my blog from Jekyll to Hugo, mainly because I have no experience with Ruby and don’t have the time to stay up to date with another language and framework.

Heatmaps are an excellent way to visualise real-time system performance, as they provide a concise and intuitive representation of response time distributions across multiple dimensions.

This is a fun talk about what goes on before your program starts executing main: Matt Godbolt mentioned the oddly named “bss” section.

Wonderful visualisations in this talk: ScyllaDB’s CTO Avi Kivity dives into how high performance distributed systems such as modern databases can make best, most efficient use of fast NVMe storage.

A normal map lets us look up items based on an exact match for the key, but here is a situation where we want to match on a superset of the search key.

I have no idea why, but a week ago my AirPods suddenly became far too quiet on Linux (Debian buster).

In the old days fitting 26" mountain bike tyres was so easy.

Profiling tools like gprof tell us about where a program spends the most time but these places aren’t necessarily the best candidates for optimisation.

The end goal here is to have Unity3D and Visual Studio Code installed on a Debian 10 Linux system with Intellisense completions working for Unity code.

(Disclaimer: I’m not recommending the use of R, this question just came up in some of Nadiah’s work.

Update 2024-02: I wouldn’t bother doing any of this, I’d just use vscode-remote in VS Code.

BeautifulSoup makes it easy to quickly scrape content from web pages.

Here is a well-known interview/code golf question: a knight is placed on a chess board.

The farmer-chicken-fox puzzle goes something like this: a farmer is at a shop, having bought a chicken, fox, and a bag of corn.

Many business problems boil down to reading data from somewhere, transforming it, and writing it somewhere else.

I’ve been using my Glacier Push utility for a while now and it has been working well.

I can never remember this. https://bitbucket.org/delx/webdl git clone https://bitbucket.org/delx/webdl cd webdl virtualenv --python python3 .virtualenv . .virtualenv/bin/activate pip install -r requirements.txt Usage: . .virtualenv/bin/activate .

Edit 2019-01-12: fixed here: numpy/pull/11977 Nadiah ran into an apparent memory leak in SciPy’s hypergeom distribution.

Using a modern GHC compiler, how much memory would this program use?

Property based testing is a great way to improve code quality since it captures logical properties of your system.

Consider an option with payout on an underlying which is a cumulative sum.

Here is a small Haskell package for pushing files to Amazon Glacier: https://github.com/carlohamalainen/glacier-push.

My Boardman Team TXC 650b hardtail mountain bike has an FSA crankset and bottom bracket.

I have a pull request to merge ghc-imported-from into ghc-mod.

I plugged in a D-Link DUB-1312 to my laptop running Ubuntu Zesty but Network Manager said that the interface was “not managed”.

2024-03-13 These days we have an excellent ecosystem with Grafana Loki, Promtail, Tempo, and friends A while ago I wrote about how to set up a structured logging service using PostgreSQL.

I had a situation, when converting old blog posts to WordPress, where I wanted to strip all the extra info on the pre tags.

Short note on Data.Proxy based on this Stackoverflow answer.

I have a pull request to merge ghc-imported-from into ghc-mod.

This blog post shows how to convert a standard Raspbian installation to full disk encryption.

I recently got two YubiKeys to try out another form of 2FA and to see how they work with my PGP setup (Enigmail and Thunderbird).

Over the xmas holidays I set up a security camera for my parents.

I was looking at an old post of mine on free monads and wondered what it would look like using operational.

I was reading some notes from QUT about using spectral graph theory to partition a graph using eigenvalues of unnormalised Laplacian.

This post has some errors; see ghc-imported-from–ghc-mod-march-2017 for the latest instructions.