The Swift compiler

In the previous step, while playing with xcrun, we discovered that there are two different swift compiler tools: swift and swiftc. If you get help for with the -h command, you will notice that they are both Swift compilers with similar options, but there is a difference.

swift

The swift tool compiles and executes swift code. If you run it without any arguments, it will launch a REPL and give you the ability to evaluate the Swift code.

You can also pass a Swift file that you want to run as a parameter. We can simply create a swift file from the command line:

echo 'print("Hello World")' > main.swift 
xcrun swift main.swift
Hello World

You can also pass additional options, such as -O to enable optimization:

xcrun swift -O main.swift

swiftc

The swiftc compiler compiles swift code and produces the result, but it doesn't execute it. Depending on the option, you can get a binary file, an assembly, an LLVM IR representation, or something else.

Unlike the swift tool, swiftc has a...