Spreading the Spread and Rest Love

JavaScript’s spread syntax has proven to be an extremely useful tool while working with immutable data structures as part of a React/Redux project.

Now that it’s widely available for objects in LTS Node 8 (as it has been for some time for other runtimes via TypeScript), it’s interesting to go back and take a look at all it can do. Read more on Spreading the Spread and Rest Love…

A Simpler Case for Functional Programming & “Elegant” Code

A lot has been written about the benefits of functional programming, but little of it is accessible to a newcomer. Some of the benefits are easy to understand from an inexperienced perspective (e.g. “it makes concurrency easier”), but others are pretty nebulous.

Chief amongst the inscrutable properties of functional programming is its “elegance.” It isn’t immediately clear what that word actually means in this context. Read more on A Simpler Case for Functional Programming & “Elegant” Code…

Understanding and Embracing TypeScript’s “readonly”

If you’ve tried to use JavaScript in a functional style, you’ve no doubt chafed at the fact that all those little objects flying around at any given time are about as far as they can possibly get from immutable. You can, of course, be careful to write code that never mutates an object, but while good practices improve your code, they’re weak defenses against bugs.

TypeScript can help you with its readonly property modifier. With readonly, you can rely on TypeScript’s static analysis to enforce and flag mutations in your codebase.
Read more on Understanding and Embracing TypeScript’s “readonly”…

Lazy Sequences with ECMAScript 6 Generators

Generators are an ES6 feature that started receiving a lot of attention a few years ago because of their potential to ease some of the pain associated with writing asynchronous code. However, with the emergent async/await proposal (mere syntax sugar around generators and promises), some of the shine has worn off, and generators aren’t getting the same amount of attention they used to.

This is a shame, because even if you disregard their uses in asynchronous code, generators are still pretty cool in their own right. I’m going to explore some of the ways you can use them to implement lazy sequences.
Read more on Lazy Sequences with ECMAScript 6 Generators…

Implementing the Elm Architecture in ClojureScript

The Elm architecture is a simple and straight-forward alternative to the common model-view-controller architecture, and it’s well suited to functional programming.

In brief, the Elm architecture uses a data structure to render a UI, the UI fires actions, and actions are used to update the data structure. This is the same sort of uni-directional flow that React.js uses and the one that Ember.js has been gravitating toward in place of two-way data bindings.

Read more on Implementing the Elm Architecture in ClojureScript…

RSchema-Hamster: Schemas for Shaping Immutable Data

RSchema-Hamster is a Ruby gem that lets you use Hamster’s persistent data structures to define and validate the shape of your data via RSchema.

What for?

In order to clarify my designs, reduce mistakes, and leave code easier to change than when I found it, I:

Read more on RSchema-Hamster: Schemas for Shaping Immutable Data…

Timeouts in ReactiveCocoa

On my current project we are using ReactiveCocoa to manage Core Bluetooth’s asynchronous callbacks when communicating with a Bluetooth Low Energy device in an iOS app. John Fisher recently explained how he’s used ReactiveCocoa to chain asynchronous operations together in this same project.

As with any application that communicates with a remote device/server, we’ve run into the need for timeouts when we don’t get an expected response in a reasonable amount of time. This got me to wondering if there might be something built into ReactiveCocoa to help with this problem. And it turns out there is! There’s a -timeout:onScheduler: operator available for use on any RACSignal. In this post I’ll show a simple example of how -timeout:onScheduler: can be used to manage a long-running asynchronous task.

Read more on Timeouts in ReactiveCocoa…

Easy Asynchronous Operations in iOS with ReactiveCocoa

Dealing with asynchronous operations is a common problem in mobile development. To keep our app’s user interface as fast and responsive as possible, we need to offload network requests, resource loading (e.g., images), bluetooth operations, and file I/O onto a background thread.

Calling one asynchronous routine and responding to its result is a relatively simple matter, but what happens when several different asynchronous operations must be executed in some set order (serialized)? Apple has built in support for queuing asynchronous operations with NSOperationQueue and Grand Central Dispatch, but there’s another solution: using a functional reactive approach with Reactive Cocoa. Read more on Easy Asynchronous Operations in iOS with ReactiveCocoa…

Funkify and Pattern-Proc: Messing with Ruby for Fun (but probably not profit)

Partial application is awesome. I love it. Same goes for functions as first-class citizens. I wish these were features in every language. I’m working in Ruby right now, and every time I use map() or reduce(), I find myself wishing I had them.

class MyClass
  def negate(x)
    -1 * x
  def add(x, y)
    x + y
obj = MyClass.new
values = [1,2,3]
# this is needlessly verbose
values.map do |val| 
end # [-1, -2, -3]
# this is disgusting
# Ruby, why u no allow this?
values.map(&obj.negate) # although dropping the & would be even better
# And how about instead of this
values.map do |val|
  obj.add(2, val)
# we could just do this?

Funkify to the Rescue

To overcome these limitations (and because it sounded fun), I started looking for a gem that would help with writing code that supports partial application. Read more on Funkify and Pattern-Proc: Messing with Ruby for Fun (but probably not profit)…