Posts

Interactive Kotlin with kscript and fswatch

Experimenting with snippets of code and getting rapid feedback is an effective way to get up to speed with a new language or library. I’ve been playing around with Kotlin and Λrrow at work this week, so have been looking for tools that help achieve this workflow. Worksheets in IntelliJ provide some of this functionality, but personally I prefer the immediacy of a text editor and the command line for this kind of thing.

Functional Design Patterns in Scala: Monads

Learning (and subsequently trying to explain) monads has become something of a rite of passage in functional programming. Like many developers, I struggled initially to understand precisely what type of thing monads are, despite using them on an almost daily basis. The most helpful description I have come across is given by Noel Welsh and Dave Gurnell in Scala with Cats:

“A monad is a mechanism for sequencing computations.”

Functional Design Patterns in Scala: Monoids

Monoids are used to describe an aggregation pattern: whenever we need to combine values of a particular type, a monoid instance helps abstract the mechanics of the aggregation from the program’s business logic. In this post, we will use the LCD Digits kata that we tackled previously as a motivating example for applying this pattern. The goal here is to transform a sequence of input digits into a string resembling their representation on an LCD display.

Scrap the Boilerplate in Scala with Lenses

Case classes provide a convenient way of working with immutable objects in scala. Manipulating fields within them can be tedious, however. In this post, we will look at how lenses can be used to abstract over this complexity while preserving the benefits of immutability.

Agile Estimation For Distributed Teams

The scrum teams I currently work with use Planning Poker to estimate the size of user stories. This has proved to be an extremely useful activity, and we rely on it to plan work for upcoming sprints. In the past, we used special card decks for these games, which worked well when everyone was based in the same room. However, with team members now distributed across two continents, this quickly became less effective.

Steve Reich’s Clapping Music with Scala and Akka

Using functions to express musical ideas is nothing new: Harmony, time signatures, the relations between notes in a scale and musical form all have their roots in mathematics, and composers have used mathematical abstractions for millennia (see Pythagorean Tuning for a 2500-year-old example). These abstractions, however, are not always obvious from they way that music is written down, leading to a potential disconnect between composer and performer. In this post, we will use Steve Reich’s 1972 Clapping Music to show how functional programming can be used to capture an underlying musical idea.

LCD Digits Kata with Scala

I recently attended one of the coding dojos run by the London Scala User Group. It was great fun, and I’d recommend getting involved to anyone who’s interested in meeting other developers and learning more about scala and functional programming. After breaking into groups, we set about tackling the ‘LCD Digits’ problem from cyber-dojo.org. Although fairly straightforward as a programming challenge, it offers a number of ways to experiment with different functional idioms. The goal is to write a program that takes an integer, and formats this as a string composed of the ‘.’, ‘_’, “|’ and ” ” characters so that the output resembles an LCD display.