unit and acceptance testing, automation, productivity


Ruby is a programming language that prides itself of being optimized for developer happiness. Part of this optimization is on how close to natural language, or at least natural english, you can get when writing Ruby code.

One of my favourite features is unless.

unless condition do

One could be tempted to say that Swift's guard is the same thing as Ruby's unless, but that's not the case.

guard condition else {

guard is not simply a if condition == false, but a tool to enforce early returns. A guard statement will not compile without a return.

For this reason I hacked together a Swift version of unless. As you can imagine the code is pretty simple:

func unless(_ condition: () -> Bool, do closure: @escaping () -> ()) {
  guard condition() == false else {


You can find the whole code on GitHub.

I made it as a Swift Package, but I would advise against using it that way. After all, what's the point of having syntax sugar that should make your job easier if you have to import it for every file?

Much better to simply copy the code, and its tests so that it's part of your Swift module.

Get in touch on Twitter @mokagio if you have any feedback, are using this little piece of code, or want to chat about syntax sugar and how it can make our code more readable and us more productive.

Leave the codebase better than you found it.

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