Structured, concrete data — Click here to share this article on LinkedIn » I’ve moved my blog. You can view this article’s new home on my personal website here. In my last post I said that there were three fundamental approaches to representing data: abstract data types, objects, and algebraic data types. I introduced…

Two fundamental approaches to data abstraction — I’ve moved my blog. The new version of this post, which uses TypeScript rather than Flow, may be viewed here. There are three main methods of representing data which developers are likely to encounter: abstract data types, algebraic data types, and objects. Abstract data types (frequently abbreviated “ADTs”) are likely…

Adding effects and composing applicatives — This is the final part of a three-part series on effectful programming with applicative functors. In the last two posts we’ve covered what computational effects are, and how we can use them in conjunction with applicative functors to capture side effects in functional code. In part one we did this…

Modeling the reading of state — This is part two of a three-part series on effectful programming with applicative functors. In part one we saw that many imperative side effects can be encapsulated into well-behaved computational effects by modeling the side effect as a modification to state within a given context and then making this context…

Bringing structure and composability to mutable state — This is part of my series on algebraic structures. The whole series can be seen here. In my last post I introduced applicative functors, and showed how they build on plain functors to allow us to apply pure functions to values inside of special contexts. This made our code more…

In a previous post I talked about functors, data types which act as a context holding contents which can be mapped over. In this post I’ll talk about applicative functors, or “applicatives”, a subtype of functors for which additional functions are defined. In this post we’ll cover the core of…

An introduction to combinator libraries, from the ground up — While they aren’t often discussed outside of the functional programming world, combinator libraries are a common and useful technique for building functional libraries. Their core characteristic is the construction of a small set of base functions and types, and a few higher-order functions for combining them. Most importantly, the functions…

Composing catamorphisms and anamorphisms — This is part of my series on recursion schemes. In the last two posts in this series we looked at catamorphisms, which collapse a nested data structure into a value, and anamorphisms, which build a nested data structure up from an initial seed value. If we combine the two, transforming…

Building up functors, recursively — This post is part of my series on recursion schemes. In the last post in this series we looked at catamorphisms, transformations that walk a recursive data structure from the bottom up, collapsing a functor to its contained type at each step. This time, we’ll be looking another type of…