On Understanding Data Abstraction, Revisited

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2024-12-12 14:30:02

One of my meta-criteria for choosing a paper in this series is the likelihood we will cover the paper on the future of coding. I won't completely rule out covering papers I think we will do at some point. But for the most part, I've decided to steer clear of them. This paper is one I don't think we'd cover on a podcast because I'm not sure it makes for great conversation. This is one of the difficult things about the podcasting medium. Or at least the medium as I conceive it. Not all papers lend themselves to a free-wheeling discussion about the paper. A lecture might work for a paper, and a blog post almost certainly works, but some things just don't come out well in a discussion.

One class of papers I don't think translate well are those that just tell you facts of the matter. I don't mean of course that there isn't bias in these papers. But simply that the goal of the paper isn't to convince you of anything but to simply tell you about things. In some ways, this paper doesn't quite qualify. It is in fact an argument, but not about something I'd consider a real live debate for me. Are objects and abstract data types different things? I'm not sure I really care about that distinction and yet this paper has stuck with me ever since I read it. So, I want to cast this paper in a different light for you readers who may, like me, not really care about objects vs adts.

Rather than make a division between objects and adts, I want you to view this paper as bridging a divide between the values held by object-oriented programmers and those held by functional programmers. Object-oriented programmers value the ability to have multiple implementations of objects interoperate together. They want systems to be extended not modified. Functional programmers value immutability. They want to be certain that the values they have cannot change out from under them. Until I read this paper, I had believed the view that objects were about encapsulating state. In this paper, I see a very object-oriented way of programming, that constructs completely immutable objects.