So you’ve been doing high-level programming all your life, and you’ve been eyeing Rust for some time now, and you’re not sure where to start (or how to start). Well, this walk-through-like post will guide you through some of the common tasks you preform in high-level languages like JavaScript, Python, or even C#.

So, JSON in Rust?

The short answer is ‘no built-in support for JSON but…’

Well, Rust has no built-in support for JSON objects, but before you let that throw you off, Rust struct s are ~ 99% identical to JSON objects in their outer structure and the way they are defined and used. Let’s look at an example.

Say you want to define a Person JSON object with fields holding things like the full name , date of birth , and gender of a person. Here’s how you’d likely define your object in a language like JavaScript:

var person = { fullName : ' Fadi Hanna Al-Kass ' , dateOfBirth : ' 01-01-1990 ' , gender : ' MALE ' };

Here’s how you’d write this in Rust:

// Our pseudo-JSON object skeleton struct Person { full_name : String , date_of_birth : String , gender : String } fn main () { let person = Person { full_name : "Fadi Hanna Al-Kass" .to_string (), date_of_birth : "01-01-1990" .to_string (), gender : "MALE" .to_string () }; }

You’ve probably already noticed two differences between the two code snippets:

We had to define a skeleton for our pseudo-JSON object. We used lowerCamelCase with JavaScript and snake_case with our Rust code snippet. This is really nothing more than a naming convention that the Rust compiler will throw a bunch of warnings at you if you don’t follow, but it shouldn’t have an effect on the execution of your program if you so choose not to follow.

Now back to the first (and perhaps, more obvious) difference. Rust is a very (and I mean very) strongly typed programming language. That said, it needs to own as much information about your object types during the compilation process as possible. Of course, struct s are no exception, and you can really consider two ways (or more, depending on how imaginational you are) of looking at this: it is either (1) limiting or (2) validating . I wouldn’t be putting this post together had I considered strong-typing limiting.

You can always replace a strongly typed pseudo-JSON object with a HashMap to get around the static typing issue, but I’d advice against that, and I believe I can convince you to stick to the struct approach. You may, at this point, still not think so, but wait until we get to these magical little thingies called traits and then we’ll see ;-)

Nested pseudo-JSON Objects?

Sure, forward we go

Let’s design our Person JSON object in a more modern fashion. Instead of having a field containing the full_name , we can turn full_name into a sub- struct that has two fields ( first_name and last_name ). Instead of storing date_of_birth as a string that we may, at some point, need to parse down to extract the day, month, and the year from, we can store this information in a struct with three separate fields. And for our gender field, we can reference an enum value.

struct FullName { first_name : String , last_name : String } struct DateOfBirth { day : i8 , // 8-bit integer variable month : i8 , year : i16 // 16-bit integer variable } enum Gender { MALE , FEMALE , NotDisclosed } struct Person { full_name : FullName , date_of_birth : DateOfBirth , gender : Gender } fn main () { let person = Person { full_name : FullName { first_name : "Fadi" .to_string (), last_name : "Hanna Al-Kass" .to_string () }, date_of_birth : DateOfBirth { day : 1 , month : 1 , year : 1990 }, gender : Gender :: MALE }; }

Our pseudo-JSON object is now looking much cleaner and even easier to utilize. Speaking of utilization, how do we reference our fields? Well, you’ve probably guessed it already. Yes, it’s the dot operator. If you’re interested in, say, printing the full name of your Person object, here’s how you’d do that:

// The following line of code goes inside your main function right after // your person object has been instantiated, or really anywhere after the // object has been declared. println! ( "{} {}" , person .full_name.first_name , person .full_name.last_name );

and you’re probably seeing a problem here already. It would be absolutely tedious to use this approach to print out the full name of a person especially if you were to do this from multiple places in your program let alone the fact the way the print is done looks really primitive. There must be a different (perhaps, even, better) way you say. You bet there is. In fact, there not only is but are many ways you can go about handling this issue, which one of which would be the use of traits . A trait is a programmatical way of telling the compiler how to carry out specific functionalities during the build process. We’re going to use one here and learn how to write our own further below. The trait we’re about to use in a moment is called the Debug trait which basically sets out a specific printing layout for your defined enum , struct or what have you.

If you simply add #[derive(Debug)] right on top of your FullName struct definition: i.e.:

#[derive(Debug)] struct FullName { first_name : String , last_name : String }

and replace:

println! ( "{} {}" , person .full_name.first_name , person .full_name.last_name );

with:

println! ( "{:?}" , person .full_name );

You’ll end up with:

FullName { first_name : "Fadi" , last_name : "Hanna Al-Kass" }

Cool, isn’t it? Well, it gets even cooler in a bit.

But hang on a second, why did I have to replace {} with {:?} in my println statement? Or an even more proper question to ask is: what is the difference between the two? Well, so Rust has two ways of printing out stuff (there might be even more ways I am yet to discover!): a (1) Display and a Debug . Display is what you’d probably want to use to allow the program to communicate some meaningful output to your user, and Debug is what you could use during the development process. These two traits can co-exist without overlapping each other. By that I mean you can allow your object to print something with {} and something entirely different with {:?} , but that’s to be covered when we get down to writing our own trait s.

So is it possible to use #[derive(Debug)] to print out nested objects? Yes, it is, and following is how. Simply add #[derive(Debug)] right on top of your main object and every object that’s part of it and then print the object as a whole by passing it to a println function using the {:?} notation, i.e.:

#[derive(Debug)] struct FullName { first_name : String , last_name : String } #[derive(Debug)] struct DateOfBirth { day : i8 , // 8-bit integer variable month : i8 , year : i16 // 16-bit integer variable } #[derive(Debug)] enum Gender { MALE , FEMALE , NotDisclosed } #[derive(Debug)] struct Person { full_name : FullName , date_of_birth : DateOfBirth , gender : Gender } fn main () { let person = Person { full_name : FullName { first_name : "Fadi" .to_string (), last_name : "Hanna Al-Kass" .to_string () }, date_of_birth : DateOfBirth { day : 1 , month : 1 , year : 1990 }, gender : Gender :: MALE }; println! ( "{:?}" , person ); }

And your output will look like:

Person { full_name : FullName { first_name : "Fadi" , last_name : "Hanna Al-Kass" }, date_of_birth : DateOfBirth { day : 1 , month : 1 , year : 1990 }, gender : MALE }

Our output is looking pretty verbose already, and you may not like that. Is there a way to manipulate this output in terms of re-arranging its layout or limiting the amount of information being displayed? You bet there is, and it’s through writing our own Debug trait instead of using a derive d one. I think it’s better to introduce one more thing right before we get down to business with trait s, and that is Rust’s OOP -like paradigm. I call it OOP -like because Rust doesn’t consider itself an Object-Oriented Programming Language, but sure that in no way means we can’t do OOP in Rust. It just means OOP is done differently. To be more precise, OOP in Rust is done in a way Rust wouldn’t consider OOP .

Up until now, we’ve only been working with struct s and enum s. You’ve probably already noticed that we used them to store data, but no logic (constructors, functions, destructors, etc) was added to them. That’s because that’s not where the functions go. before I further explain this, let’s look at a tiny Python class and discuss how its alternative can be written in Rust. Say you have a Person class with a constructor that takes a first_name and a last_name and provides two separate getter functions that give you these two string values whenever you need them. You’d write your class something as follows:

class Person : def __init__ ( self , firstName , lastName ): self . firstName = firstName self . lastName = lastName def getFirstName ( self ): return self . firstName def getLastName ( self ): return self . lastName

Notice how we have our fields and functions mixed together inside a single class. Rust separates the two. You’d have your fields defined inside a struct and an impl containing all relevant functions. So, when interpreted, our Python class would look in Rust as follows:

struct Person { first_name : String , last_name : String } impl Person { fn new ( first_name : String , last_name : String ) -> Person { return Person { first_name : first_name , last_name : last_name }; } fn get_first_name ( & self ) -> & str { return & self .first_name ; } fn get_last_name ( & self ) -> & str { return & self .last_name } }

And to instantiate the object and access/utilize its functions, we do the following:

let person = Person :: new ( "Fadi" .to_string (), "Hanna Al-Kass" .to_string ()); println! ( "{}, {}" , person .get_last_name (), person .get_first_name ());

You’ve probably already looked at the code and thought to yourself “aha, Person::new() must be the constructor” to which you’d definitely be right. however, one thing you need to keep in mind is that Rust has no concept of a constructor per se. Instead, we define a static function that we use to instantiate our object. This also means new is not a keyword nor is it the required name of your entry point to your object; it can really be anything but new is the convention.

In short, your class constructor is a static function located inside an impl and turns an object of the type of the class you’re instantiating (Person in our case).

Traits

If this doesn’t turn you into a Rust fanatic, I don’t think anything will. Sad :-(

A trait is nothing but a language feature that tells the compiler about a type-specific functionality. The definition of a trait may be confusing as heck to you, but it’ll all settle for you with the first example or two.

Remember how we were talking about classes with constructors, functions, and destructors? Well, we’ve already discussed how constructors and functions are done in Rust. Let’s talk a little about destructors. A destructor is a class function that invokes itself once the class is out of scope. In some low-level programming languages like C++, a class destructor is normally used to deallocate all allocated memory and preform some house cleaning. Rust has an impl destruction functionality ( trait ) called Drop . Let’s look at how this trait can be implemented and invoked:

Let’s say you have a Response object you return to a HTTP validation layer that sends it to an end-client. Once this operation is complete, you have no business in maintaining this Response object, so it’ll delete itself once it’s out of scope. Let’s start by defining this structure:

struct Response { code : i32 , message : String } fn main () { let res = Response { code : 200 , message : "OK" .to_string () }; }

Now let’s add a Drop trait to our object and see when Drop is invoked:

impl Drop for Response { fn drop ( & mut self ) { println! ( "I ran out of scope. I'm about to be destroyed" ) } }

If you try to run the complete program now, i.e.:

struct Response { code : i32 , message : String } impl Drop for Response { fn drop ( & mut self ) { println! ( "I ran out of scope. I'm about to be destroyed" ) } } fn main () { let res = Response { code : 200 , message : "OK" .to_string () }; }

You’ll see the following output right before the program finishes executing:

I ran out of scope. I'm about to be destroyed

Let’s look at another example. If you’ve ever done any scientific computation in Python, chances are you’ve overloaded some of the arithmetic operations ( + , - , * , / , % , etc). A vector class with + overloaded would look something like the following:

class Vector : def __init__ ( self , a , b ): self . a = a self . b = b def __add__ ( self , otherVector ): return Vector ( self . a + otherVector . a , self . b + otherVector . b ) def __str__ ( self ): return "Vector(%s, %s)" % ( self . a , self . b )

And if you were to add two Vector objects together, you’d so something like the following:

v1 = Vector ( 1 , 2 ) v2 = Vector ( 5 , 7 ) v3 = v1 + v2

And print the result as follows:

print ( v3 )

This will print the following:

Vector ( 6 , 9 )

Hmm.. Let’s see how we could go about implementing this in Rust. First, we’d need to somehow find a way to add objects (i.e., overload the + operator). Second, we’d need to be able to give our object to println and see it print something like Vector(#, #) . Lucky for us, both of these features are available as trait s we can implement. Let’s chase them one at a time. We’ll start with the Add trait .

Here’s our Rust Vector object:

struct Vector { a : i32 , b : i32 }

Then we add the constructor :

impl Vector { fn new ( a : i32 , b : i32 ) -> Vector { return Vector { a : a , b : b }; } }

We, then, add the + operation overloaded to our Vector struct as follows:

use std :: ops :: Add ; impl Add for Vector { type Output = Vector ; fn add ( self , other_vector : Vector ) -> Vector { return Vector { a : self .a + other_vector .a , b : self .b + other_vector .b }; } }

At this point, we can have the following in our main function:

let v1 = Vector :: new ( 1 , 2 ); let v2 = Vector :: new ( 5 , 7 ); let v3 = v1 + v2 ;

But we can’t print quite yet. Let’s implement this:

use std :: fmt ::{ Debug , Formatter , Result }; impl Debug for Vector { fn fmt ( & self , f : & mut Formatter ) -> Result { return write! ( f , "Vector({}, {})" , self .a , self .b ); } }

Now we can print v3 as follows:

println! ( "{:?}" , v3 );

And get the following output:

Vector ( 6 , 9 )

Your final program should look like the following:

struct Vector { a : i32 , b : i32 } impl Vector { fn new ( a : i32 , b : i32 ) -> Vector { return Vector { a : a , b : b }; } } use std :: ops :: Add ; impl Add for Vector { type Output = Vector ; fn add ( self , other_vector : Vector ) -> Vector { return Vector { a : self .a + other_vector .a , b : self .b + other_vector .b }; } } use std :: fmt ::{ Debug , Formatter , Result }; impl Debug for Vector { fn fmt ( & self , f : & mut Formatter ) -> Result { return write! ( f , "Vector({}, {})" , self .a , self .b ); } } fn main () { let v1 = Vector :: new ( 1 , 2 ); let v2 = Vector :: new ( 5 , 7 ); let v3 = v1 + v2 ; println! ( "{:?}" , v3 ); }

Oh, and you know how I said {} is used to communicate output to the user while {:?} is usually used for debugging purposes? Well, it turns out you can overload the Display trail (available under std::fmt as well) to print your object using {} instead of {:?} .

So, simply replace:

use std :: fmt ::{ Debug , Formatter , Result };

With:

use std :: fmt ::{ Display , Formatter , Result };

And:

impl Debug for Vector {

With:

impl Display for Vector {

And:

println! ( "{:?}" , v3 );

With:

println! ( "{}" , v3 );

And voila, you’re all set.

Statements vs. Expressions?

At this point, I’m a bit tired of having to included unnecessary keywords in my code snippets, so I thought I’d introduce the concept of statement-vs-expression in Rust.

So, basically statements that don’t end with a semi-colon ( ; ) return something and they even have a special label: expressions . Without getting into too much detail and get you all confused, let me instead throw a little snippet at you and let you sort it out in your head.

So, let’s say you have a function that takes two i32 arguments and returns the sum of the two values. You could have your function written like this:

fn sum ( a : i32 , b : i32 ) -> i32 { return a + b ; }

or you could have the shorthand notation of the function by using an expression instead of a statement:

fn sum ( a : i32 , b : i32 ) -> i32 { a + b }

From this point on, I will be using expressions whenever possible.

Our Journey into the Specifics

We’re now going to dive into the basics of Rust.

Variable/Object Declaration

We’ve been declaring objects and variables all over the place already, but perhaps there’s more to them than what’s been covered already. If you want to declare an integer x and assign the value 2 to it, you could do so as follows:

let x = 2 ;

But if you were to write an operating system, a kernel module, and/or an application that runs on an embedded system, the size of your object really matters, and chances are you’ll need to control these sizes. Unless you dive into the specifics of the design of the compiler of Rust, you really have no idea how many bits are used to store your variable. There must be a better way to carry this out, and here’s how. Rust allows you to specify the type of your object with a slight edit to your statement. Instead of writing your variable declaration like this:

let x = 2 ;

You could write it like this:

let x : i8 = 2 ;

And you know for sure that your variable is stored as an 8-bit integer.

Read more about Primitive Types and Object Declaration here

Mutability

By default, objects and variables in Rust are immutable (not modifiable after they’ve been declared). Something like the following won’t work:

let x : i8 = 2 ; x = 3 ;

To be able to change the value of x , we need to tell the compiler to mark our variable as mutable (able to change value after it’s been declared). This introduces a slight change to our declaration that’s pretty intuitive; you simply add the keyword mut on the left side of your object declaration statement like this:

let mut x : i8 = 2 ;

And now the following will work like a charm!

x = 3 ;

Type Aliases

Rust has a keyword called type used to declare aliases of other types. Say you want to use i32 across a whole class , module or even across your whole application, and for clarity’s sake you’d rather use Int instead of i32 to reference 32-bit integers. You could define your Int type as follows:

type Int = i32 ;

And now to use your new type, you could define your variables like this:

let var1 : Int = 10 ; let var2 : Int = 20 ;

And so on.

Functions

Function declarations are pretty intuitive and straightforward. Say you want to write a greeting function that prints out the test "hello there!" over stdio . You’d write your function as follows:

fn greeting () { println! ( "hello there!" ); }

What if you want to pass the string to the function instead of hard-coding a specific value? Then, you’d write it like this:

fn greeting ( message : String ) { // TODO: Implement me }

Multiple function arguments? Sure! Here’s how:

fn greeting ( name : String , message : String ) { // TODO: Implement me }

Functions with return values? Here’s how:

fn add ( a : i32 , b : i32 ) -> i32 { a + b }

i32 is a 32-bit integer type in Rust. You can read more about Rust’s support for numeric types here.

Remember that we’re using an expression in the code snippet above. If you wanted to replace it with a statement return a + b; will do.

Closures

The easiest definition of a closure I can give is that a closure is a function with untyped arguments. If you were to write a function that multiplies two numbers together and return the product, you’d do so as follows:

fn mul ( a : i32 , b : i32 ) -> i32 { a * b }

This function can be written as a closure as follows:

let mul = | a , b | a * b ;

And then you can call it the exact same way you’d call a function, i.e.:

println!("{}", mul(10, 20));

If you, for whatever reason, want to strongly-type your closure arguments, you can do so by defining their types the same way you’d define function arguments, e.g.:

let mul = | a : i32 , b : i32 | a * b ;

And you can even strongly-type your closure return type as follows:

let mul = | a : i32 , b : i32 | -> i32 { a * b };

But that’ll require you to wrap your closure content within two curly brackets ( { and } ).

You can read more about most of the cool stuff you can do with closure s here.

Function Pointers

If you’re coming from a solid background in languages like C and C++, chances are you’ve worked with function pointers a lot. You’ve probably even worked with function pointers in languages like JavaScript and Python without ever coming across the name. At its core, a function pointer is a variable holding access to a specific memory location representing the beginning of the function. In JavaScript, if you were to have the following:

function callee () { // TODO: Implement me } function caller ( callback ) { // TODO: Implement a task callback (); } caller ( callback );

It can be said that “ caller is a function that takes an argument of type function pointer (which in this case is our callee function)”.

Rust isn’t that flexible when it comes to function pointers though. If you were to pass a function pointer to a function, the calling function needs to have a somewhat hard set on callback function specifications; your calling function needs to specify the arguments and the return type of the callee function. Let’s discuss a use case where you may want to use a function pointer.

Say you’re creating a struct called CommandInterface that will contain two fields: (1) a command string, and (2) a function pointer pointing to the function to be executed with the specified command. Let’s start by defining the outer skeleton of our interface struct :

struct CommandInterface { str : String , exec : fn () -> i8 }

Here we’re telling the compiler to expect our function pointer to have no arguments and return an 8-bit integer. Let’s now define a function according to these specifications:

fn ls () -> i8 { // TODO: Implement me return 0 ; }

Our function needs not have a specific name. I’m only naming it after the command you’re about to see below to maintain a convention.

Let’s now define our function, set the function pointer, and see how we could use the function pointer in calling our function.

let cmd = CommandInterface { str : "ls" .to_string (), exec : ls // points to the ls function declared above }; ( cmd .exec )();

The parenthesis ( () ) around cmd.exec are a syntax requirement. If you forget to add them, the compiler will throw an error at you.

But what about functions with arguments? Say we want to pass some command arguments to our function, how would we do that? Well, this is pretty easy and it’ll require very slight changes. You could replace:

exec : fn () -> i8

with:

exec : fn ( arg1 : String , arg2 : String ) -> i8

and:

fn ls ( arg1 : String , arg2 : String ) -> i8

with:

( cmd .exec )();

with something like this:

( cmd .exec )( "-a" .to_string (), "-l" .to_string ());

In a practical world, it’d be better to pass a vector of arguments but I intentionally ignored vectors just to keep things clean.

Conditionals

When it comes to code path redirection, Rust has the three keywords you’ll likely find in most programming languages out there: if , else , and else if . If you’ve worked with languages like C , C++ , C# , Java , and JavaScript , then you already know how to work with conditional expressions in Rust. Here’s the trick: conditional expressions in Rust are done exactly the way they’re done in the languages I just mentioned, except without the wrapping parenthesis, e.g.:

The following JavaScript code:

if ( x == 0 || x == 2 ) { // TODO: Implement me } else if ( x == 1 ) { // TODO: Implement me } else { // TODO: Implement me }

is written in Rust as follows:

if x == 0 || x == 2 { // TODO: Implement me } else if x == 1 { // TODO: Implement me } else { // TODO: Implement me }

And that’s really all there is to it when it comes to code path redirection.

You might, however, be used to using the ? operator for quick things like “if x is even do this and if x is odd do that”, e.g.:

// The following JavaScript statement sets `res` to 'even' if `x` is an even value, and 'odd' if `x` is an odd value var res = x % 2 == 0 ? ' even ' : ' odd ' ;

In Rust, the same can be written as follows:

let res = if x % 2 == 0 { "even" } else { "odd" };

Matching (aka pseudo-Switch-Case Statements)

Matching is your typical switch case code block plus the ability to return something. If you were to compare integer x against a number of different values, using classical if - else -- else if gets pretty tedious really quickly, so developers tend to resort to switch case statements. Referring back to our x example, the following JavaScript compares x against 5 different values (cases):

switch ( x ) { case 1 : console . log ( ' x is 1 ' ); break ; case 2 : console . log ( ' x is 2 ' ); break ; case 3 : console . log ( ' x is 3 ' ); break ; case 4 : console . log ( ' x is 4 ' ); break ; default : console . log ( ' x is something else ' ); break ; }

The snipper above can be written in Rust as follows:

match x { 1 => println! ( "x is 1" ), 2 => println! ( "x is 2" ), 3 => println! ( "x is 3" ), 4 => println! ( "x is 4" ), 5 => println! ( "x is 5" ), _ => println! ( "x is something else" ) };

_ is how you handle default cases

But things don’t end here; there’s more to match statements. Like I mentioned above, you can actually return a value or an object from a match statement. Let’s do some refactoring to our code snippet above and make it return the actual string instead of printing it to screen:

let res = match x { 1 => "x is 1" , 2 => "x is 2" , 3 => "x is 3" , 4 => "x is 4" , 5 => "x is 5" , _ => "x is something else" }; println! ( "{}" , res );

That will print the exact same thing except it handed you back the string instead of printing it, and you printed it.

match can work with sophisticated objects and patterns. Read more about it here.

Loops

Loops are a very interesting subject in Rust. The language currently has three approaches to any kind of iterative activity. These three approaches use three separate keywords: for , while , and loop .

The for loop is used when you’ve already decided the number of times you’d like to iterate. For example, the following will loop 9 times and print the values 0 through 9 :

for i in 0 .. 10 { println! ( "{}" , i ); }

This interprets to the following Python code:

for i in range ( 0 , 10 ): print ( "%d" % i )

You can also iterate over a list using a for loop as follows:

for i in & [ 10 , 20 , 30 ] { println! ( "{}" , i ); }

This is equivalent to the following Python code:

for i in [ 10 , 20 , 30 ]: print ( "%d" % i )

for loops can also preform some sophisticated tasks. For instance, if you have the string "hello

world

my

name

is

Fadi" and you want it up split it up using the linefeed (

) delimiter, you can use the lines() function. This function returns an enumerator containing both the substring and the line number. So something like the following:

let my_str_tokens = "hello

world

my

name

is

Fadi" .lines (); for ( line_no , term ) in my_str_tokens .enumerate () { println! ( "{}: {}" , line_no , term ); }

Results in this:

0: hello 1: world 2: my 3: name 4: is 5: Fadi

The above example is equivalent to the following Python code:

myStrTokens = "hello

world

my

name

is

Fadi" . split ( "

" ) for i in range ( 0 , len ( myStrTokens )): print ( "%d: %s" % ( i , myStrTokens [ i ]))

The while loop is used when you’re not sure how many times you need to loop. It works the exact same way a while loop works in languages like C, C++, C#, Java, JavaScript, and Python. Here’s a JavaScript example:

bool status = true ; while ( status ) { // add some case that can set `status` to false }

The snippet above can be translated into Rust and look like the following:

let status : bool = true ; while status { // add some case that can set `status` to false }

The loop loop is used when you want to run your loop indefinitely until a terminating statement is reached. An example of when this would come in handy is when you have a web server with request handlers each assigned a thread. In a case like this you wouldn’t want to have this:

let status : bool = true ; while true { // add some case that can set `status` to false }

When you could actually have this:

loop { // add some case that can break out of the loop }

“Rust’s control-flow analysis treats this construct differently than a while true, since we know that it will always loop. In general, the more information we can give to the compiler, the better it can do with safety and code generation, so you should always prefer loop when you plan to loop infinitely” - Quoted from https://doc.rust-lang.org/book/loops.html

Here’s one more thing you’d probably like about loops in Rust. Loops can have labels. Labels are extremely useful when working with nested loops. Here’s a JavaScript example:

var status1 = true ; var status2 = true ; while ( status1 ) { while ( status2 ) { status1 = false ; status2 = false ; } }

The snippet above can be written with labels as follows:

'outer_loop : loop { 'inner_loop : loop { break 'outer_loop ; } }

Read more about loops here.

I think I’ve covered enough in this post and will stop right here. More stuff is coming in upcoming posts though, so stay tuned.