Common JSON patterns in Haskell, Rust, and TypeScript

A lot of web development is transforming JSON one way or another. In TypeScript/JavaScript, this is straightforward, since JSON is built into the language. But can we also achieve good ergonomics in Haskell and Rust? Dear reader, I am glad you asked! 🙌

The comparisons we will see are not meant to show if one approach is better than another. Instead, it is intended to be a reference to become familiar with common patterns across multiple languages. Throughout this post, we will utilize several tools and libraries.

The core of working with JSON in Haskell and Rust is covered by:

  • Aeson: a Haskell JSON serialization/deserialization library1.
  • Serde: a Rust JSON serialization/deserialization library.

The ergonomics is then improved in Haskell by grabbing one of the following options2:

We’ll go through typical use-cases seen in TypeScript/JavaScript codebases, and see how we can achieve the same in Haskell and Rust.

Read more →

Visual Studio Code on iPad

With Apple increasing their focus1 on making the iPad a viable device for work, it is time to revisit using my iPad as a workstation for programming.

I rely heavily on command-line tools and language-specific tools (rust-analyser, node, ghcide, etc.) for my day-to-day programming, and my current setup features:

  • Blink with mosh to a remote server.
  • Neovim and wemux on the remote server.
  • iSH to play around with very simple CLI needs locally on the iPad.

On my computer, I use Visual Studio Code, and it’s long been a wish to get that running somehow on my iPad. This is an attempt to make VS Code available on the iPad under the restrictions that we have to deal with.

Read more →

Live Migration of DynamoDB Tables

Recently I was faced with the challenge of having to migrate a set of AWS DynamoDB tables to completely new tables. We wanted to achieve this without affecting any of our users, and without having a maintenance window while migrating data from the old table to the new ones.

The following will be a very high-level overview of how you:

  • Get all your DynamoDB events onto a queue
  • Replicate your DynamoDB tables to the new tables (or even a different region)
  • Continuously synchronize your original tables to your new tables
    • Restart the migration if you made an error
  • Complete the switchover after validating everything looks OK

Read more →

Mobile Haskell (iOS)

A lot of progress has been going on to make Haskell work on mobile natively, instead of e.g. generating JavaScript via GHCJS and using that. Unfortunately, not much documentation exists yet on how to build a project using these tools all together.

This post will be an attempt to piece together the tools and various attempts into a coherent step-by-step guide. We will start by setting up the tools needed, and then build an iOS app that runs in both the simulator and on the device itself (i.e. a x86 build and an arm build).

Read more →

Using Electron with Haskell

Compiling SCSS and JavaScript in Hakyll

This seems to be an often asked question, so I thought I’d try and share the approach that I’ve arrived at after having explored a couple of solutions to the problem. If you want to see the full code in action, check out the repo for the codetalk.io site (linking to v1.0.0 is intended, in case the code changes later on).

Read more →

Briefly on the purpose of Functors, Applicatives and Monads

Setting up UnrealIRCd and Anope IRC Services on EC2

Having recently discovered sameroom.io I wanted to update the codetalk IRC server to be compliant with their authentication method. This basically just meant enabling SASL support, but while I was tinkering with stuff anyways, I thought I might as well streamline the setup process for the IRC server. In short, everything is fully automated and set up on AWS using EC2 and S3.

This will go through the process of doing exactly that, by talking about:

Read more →

S3 bucket specific policy

I have recently started caring a bit more about security on my AWS applications, and to this end Identity & Access Management (IAM) users are a great way to limit access to a need-to-use-only basis.

Recently I set up my IRC server to download its configuration and install files from an S3 bucket. This meant that it needed to have read access to a specific bucket, and for this an IAM role was created.

There are two ways to generate policies:

I will generally advise to either use the generator completely or at least use it for the basis of the policy you want to create.

Read more →

Irssi notifications on iOS and Android