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Swift & C++
Started learning C++ mixed with a bit of Swift
This all started when I got an email about a job interview, but the interview and the position would be in C and C++. These are two languages I have touched, but wouldn’t consider myself a strong programmer in. So to prep for the interview, I did a few things to get myself excited about C++ and begin learning it.
The first of which was just relearning how to compile the files and fumbling together a project. I started with just manually invoking clang and then running the executable after, worked my way up to multiple files, and then got distracted by getting Swift and C++ compiling together with cmake. I thought this was cool, since I saw it get released, but for some reason, I decided to avoid C++ til now. I think I am a much stronger programmer than I was 2 years ago when I first touched C++, and that helped me have less to learn when learning the language, also not having the restrictions that school imposes on you when you learn new things. I could use any version of C++ I wanted, any project. I was actually having fun.
Two’s Compliment
Two’s Complement is a podcast that I stumbled into and listen to semi-regularly. The most recent podcast they published was about C++ and Rust Talk about the strengths and weaknesses of both. I was more excited about this topic as it was an indirect way to learn more about C++. He mentioned a few other talks he did, one about C++ style, which I would love to see from other languages. The other previous talk he mentions is Correct by Construction talks about building API’s that the compiler aids you in using correctly. C++ building on top of C inherited a bunch of ways to shoot yourself in the foot. It has to be this way so that the C code from the 70s can compile and run today. If you break that, it’s no longer C and C++, it’s something new, and if you’re going to do something new, you should break or remove as many of the bad ways of doing something as you can.
Swift
This is why I think Apple is building Swift and building it the way they are. At the surface level, Swift is kinda bad language or at least no better than Java, Go, Python, for any specific use case. I think the goal with Swift is to be the programming language for building distributed systems, user interface down to Systems programming. I think a large part of the complexity in our world is just gluing different languages and systems together.
Every language is designed to solve a problem, and Swift is being built to replace as much, if not all, of Apple’s source code and also do so incrementally. You can’t rewrite large systems and not expect something to break. Sure, you can calculate the loss in some way, but is the new language worth the risk, cost slow down to build on top of what you have? Apple doesn’t really get much credit for it, but it effectively replaced Objective-C. I think even the Objective-C runtime is written in Swift now, which is pretty funny. Now they are working on C++ and projects they depend on, like LLVM, Foundation DB, and I’m sure many internal repositories.
Swift & C++
Circling back to the Correct by Construction video, a lot if not all the points made are defined away in Swift. This is recent with Swift getting what it calls Not Copyable (~Copyable) types meaning you either have the thing or you gave it to someone else. One of three things happens with data when programming: two parts of your code have a reference to something like a resource. Two parts both have their own copy or one part hands the resource off to another part, giving up its ability to access or mutate the data anymore. This last part isn’t common or at least not commonly used, I guess C++11 had the beginnings of this. Rust is the most well-known language for enforcing this idea of not sharing data.
Apple is currently adding a bunch of syntax and features to Swift to have its own approach to what’s referred to as ownership and lifetimes. This is needed to express many of the things in C++ that they are trying to migrate away from, as well as to do low-level resource-constrained programming.
Learning from C++
Anyway, finally sitting down and spending some time learning C++ and working on the Ray tracing in one weekend book as well as Doing some Leetcode puzzles in C++, it’s been really funny to see how much Swift borrows from C++, and I also understand why so much of the world is written in C++ now. The language has pretty much been the live Beta for programming languages yes, there is Haskell and the functional and Lisp side of programming langues, but Swift also steals from those languages with its protocols and value types.
Something kinda demonic but kinda fun is my leetcode solutions are in C++, but I wrote the tests and ran the project in Swift. So no CMake or other C++ build systems just letting swiftc and internally clang take care of that, which allows me to leverage Swift for what it’s really good at right now, high-level abstraction programming. This is kinda a fun medium to move between, you have a high level of concurrency safe language and the ability to drop down to low level control with various degrees of safety. Swift is, in a way, gradually typing the computers that we are stuck with.
Wrap up
Anyway, this was more about me having a bit of fun learning C++, appreciating. What Swift is trying to do, and also where it came from.
Thanks for reading, Zane.