TL;DR – use def all the time, and things just work. Remember that old adage from Java, “Never call a nonfinal method in your constructor”?Yeah, that still applies in Scala, and it keeps biting me. It’s easier to get wrong in Scala. Here’s a refresher:When a class is instantiated, the superclass is initialized first. Its …
Your home and your bank account: one of these is an asset, and one is money. Enter the real estate market, and they become interchangeable, with substantial effort. Matter and energy: they’re the same at some level. If it were easy to go back and forth, we’d all move around at the speed of light. …
In Surfaces & Essences[1], Hofstadter talks a lot about abstraction. Adults abstract more than children. For evidence, take the Tower of Hanoi game: move the stack to another peg, moving one disk at a time and never putting a bigger disk atop a smaller disk. It takes 7 moves for 3 disks. When 8-yr-old children …
I postulate that comments are a code smell. Craig Buchek suggests a possible counterexample: # Let this raise its exception if the fields don’t exist as expected.user = c.get_setting(‘username’) How else could one express the intention here, he asks? I say, the output of a function should be expressed in its return value. Exceptions are …
In philosophy, there are very few things that can’t be doubted. The basic laws of logic are among them. There’s one that seems completely obvious and indisputable to normal people: Law of Identity: Everything is identical to itself. In my audiobook, the professor is going on about how not only is this statement true in …
“In cognitive science, we only use the lambda-calculus model of computation,” says Dr Philipp Koralus (Phd, Philosophy & Neuroscience, on his way to be a lecturer at Oxford). “We want to talk about what the system is doing, and abstract the how.” Two models of computation: lambda calculus and the Turing machine. Teacher and student, …
Read moreTwo Models of Computation: or, Why I’m Switching Trains
Writing tests first forces you to think about the problem you’re solving. Writing property-based tests forces you to think way harder.— Jessica Kerr (@jessitron) April 25, 2013 What is this property-based thing? Property-based tests make statements about the output of your code based on the input, and these statements are verified for many different possible …
People say, “Oh, Ruby has functional programming! We pass blocks around all the time!” I’m sorry to inform you: Ruby blocks are not first-class functions. Functional programming is so called because we find it useful to pass functions as values. When we do that, we expect that the function can be called and: it’ll get …
Functional style makes code more maintainable. How? One way makes processing into a flow of data with discrete steps. Another way separates flow from context, making the context swappable. This post illustrates both. We’ll go from an imperative style to a more and more functional style. Scala is a good language for this illustration, since …
For all the programmers who don’t deeply grok the lambda calculus terminology — Say you are about to call a method on a container, and that container can give you something back of type Tweet. What you really want isn’t a Tweet, but some part of it, say Tweet.getId(). What if, instead of getting the Tweet …