I started trying Swift on the server for backend work. With macOS, it is all fairly clear in terms of how to start using Swift (at least there is Xcode), but on Linux it turned out to be much less obvious.
The Swift.org website has instructions for OS X and for Ubuntu (14.04 and 15.04). I was immediately happy to see that they provide precompiled binaries. In short: download the archive, download various keys and signatures, verify the archive signature just in case, unpack the archive, and run export so the command can be executed from the console. For example:
swift --version
Swift version 2.2.1-dev (LLVM da67bff217, Clang 81d0486fb2, Swift 82adb8fc96)
Target: x86_64-unknown-linux-gnu
Start with some simple Hello World: just create a small project that prints text to the console, something like:
import Foundation
print("hello world")
Then you need to check whether it works. Run:
swift build
error: unable to invoke subcommand: /home/webserver/swift-2.2.1-SNAPSHOT-2016-04-23-a-ubuntu14.04/usr/bin/swift-build (No such file or directory)
Surprise! The release version of Swift 2.2.1 does not include swift-build. In other words, we cannot build a project with the release version. That is a bit mind-blowing. You start googling and it turns out that you need to download the dev version of Swift. And that is a pre-release version of Swift 3.0.
That version has everything, the project builds, the binary runs, and it prints text to the console. But it is still strange that the tutorial from the website does not work with the release version. Although they say it was present in previous releases.
The saddest part is that you still cannot even send network requests from open-source Swift: NSURLRequest is not implemented in Foundation, which means my idea of using CouchDB through its REST API can be postponed for now. And on GitHub there is still this line in the description of Swift's current state:
NSURLSession and related classes are not yet implemented.
You can, of course, use C libraries. For example, IBM use a CURL wrapper called CCurl. But I would prefer something out of the box, using language tools. So I will probably wait until they finally add it.
My tinkering with the Swift Express web framework showed that it is possible to build a website or REST API with it. Yesterday evening I even made a scaffold for rewriting this blog — templates are ready, routing is ready, the whole site design is rendered, only the database data remains to be wired in. And now the question is how to fetch data from the database. There are wrappers over C libraries for MySQL and MongoDB, but I still want to keep using CouchDB, since I already use it in many projects. And it has a REST API, which means the data must be fetched over network requests, which Foundation still does not provide, and I do not really want to use third-party tools because once everything is implemented, switching to built-in tools will make more sense, so I would have to rip that code out. I will wait a bit longer before rewriting my little blog in Swift :)