Intro to Clio lang: Ship performance-critical JS with ease

JavaScript’s runtime is single-threaded, which makes it a no-go for performance-critical operations. While you can implement multi-threading in your code, there is still a need for a programming language that leverages multi-threading by default.

What is Clio?

This is where Clio comes in. According to the documentation, the Clio programming language provides out-of-the-box support for multi-core usage. This means that it can run on the cloud and clusters with no problem.

Moreover, Clio compiles its code into JavaScript, so if your machine can run JavaScript, then it is definitely capable of running Clio code with no issues.

Getting started with Clio

Running Clio code

Clio has an installer, but it does not currently work properly. For this reason, we will be using the online compiler for this article.

Creating the “Hello World” app

In Clio Playground, write the following piece of code:

export fn main:
  console.log "Hello, World!"

In line 1, create the main method. Just like other programming languages, Clio requires a main method. In the end, we’ll use the export keyword to export this function. This makes it capable of being run.

Now, run the code. This will be the result:

Great! Our code works. Let’s now move on to learning the fundamentals of Clio.

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Declaring constants in Clio

To declare a constant, you have to use the following syntax:

<value> => <variable_name>

You can declare a string, like so:

"LogRocket" => websiteName

This assigns the value “LogRocket” to the variable with the name websiteName.

Likewise, you can declare an integer and a boolean:

9 => numberNine
10>3 => result

First, we create a variable with the name numberNine and assign it the value 9. Then, we create a variable called result. Is the number 10 greater than 3? Then assign it the false value.

To display these constants to the command line, write the following code:

export fn main:
  9 => numberNine
  10>3 => result
  "LogRocket" => websiteName 
  console.log numberNine
  console.log result
  console.log websiteName
  console.log f"Name of website is: {websiteName}"

In lines 5-7, we display the values of the variables that we declared earlier, and then we display a string and append the value of websiteName in the end. This will be the result:

Great! Our code works.

Declaring functions in Clio

To declare a function, use the following syntax:

fn <function_name> <parameter 1> <parameter 2> 
  <code logic goes here>

For example, this piece of code multiplies two numbers and returns a value:

fn multiply a b:
  a * b

Here, we declare a function called multiply which takes two arguments, a and b, then we multiply a and b and return the result.

You can even use console.log in your functions.

fn multiply a b:
  console.log a * b

This logs out the result of a * b .

To call these functions, write the following code:

fn multiply a b:
   a * b

export fn main:
   multiply 4 8 -> console.log

Now, let’s use our multiply function and log the result to the console. We will learn about the piping( → ) syntax later. Run the code. This will be the result:

If your function does not return a value, you can utilize the following snippet:

fn multiply a b:
  console.log a * b

export fn main:
   multiply 4 12 

This invokes the multiply function, which will log out the result to the console.

Here’s the output of the code:

Voila! The result came out as expected. In the next section, we will learn about if and else statements.

Comparisons between multiple values

This is the syntax for if/else statements.

if <condition>:
  <statement>
else if <condition>:
  <statement>
else: 
  <statement>

As an example, let’s look at the following piece of code:

fn equals a b:
  if a > b:
    console.log f"{a} is bigger than {b}"
  else if a = b:
    console.log f"{a} is equals {b}"
  else:
    console.log f"{a} is smaller than {b}"

export fn main:
  equals 40 10
  equals 10 40
  equals 10 10

Notice that we first create a function called equals, which takes in two arguments, then compare if a is larger than b. If so, then output a suitable message. Next, perform an else if statement to check whether a and b are equal. Otherwise, inform the user that a is smaller than b.

Finally, run the equals function with different datasets. This will be the output:

Great! Our code works. Let’s now dive deeper into more advanced topics.

Diving deeper into Clio

Using flows

Earlier we used the piping syntax(→). In this section, we will learn about the flows syntax.
The piping operator is used to transfer the results of a function into another function.

Look at the following snippet:

fn isBigger a b:
  a > b
export fn main:
 isBigger 10 20-> console.log 

This creates a function called isBigger that tells whether the first number is larger than the second number. Go ahead and run the isBigger function. The result of isBigger (false) is then transferred to the console.log method. As a result, false is output to the screen

You can chain multiple function calls as well. This code first creates three functions, invokes the add function, and transfers the result of this method into the square method. Finally, it transfers the result of square into console.log.

Note that you can even apply piping syntax with indentation to make your code more readable.

fn add a b:
  a + b

fn square a :
  a * a

fn subtract a b:
  a - b

export fn main:
 add 5 5 -> square  -> console.log 
 square 5 
  -> subtract 100 
  -> console.log

Declaring arrays in Clio

To declare an array and print it, use the following syntax:

[<value_1> <value_2> <value_3>] => <variable_name>
console.log <variable_name>

For example:

export fn main:
  ["LogRocket" "FreeCodeCamp" "YouTube"]  => websites 
  [2 3 4] => integers
  [true false false] => booleanValues
  console.log websites
  console.log integers
  console.log booleanValues

Let’s create an array called websites that has string values, create an array called integers, which takes integers, and then create an array called booleanValues, which contains boolean values.

Great! Let’s now learn how to map values in an array.

Mapping arrays

In Clio, to map functions to arrays, we have to use the → and the * symbol. This piece of code prints out all of the items in the array:

export fn main:
  ["LogRocket" "FreeCodeCamp" "YouTube"]  => websites 
  websites -> * 
    console.log

Notice this uses the * to tell Clio to apply the function on each item in the array. In line 4, we log out the items to the console. Here’s the result.

Let’s play with the piping syntax further. We can even add multiple functions, like so:

fn add a b:
  a + b
fn square a :
  a * a

export fn main:
  [2 3 4] => integers

  integers -> * 
    square
    -> add 1
    -> console.log

Here, we create two functions called a and b and an integers array, then tell Clio that the function will be run on every item in the array.

Beginning line 10, we apply the square method on the items, then transfer the result of the square method to the add function. This will increment the result.

Declaring hash maps

These are similar to JavaScript objects. To declare a hash map, use the following syntax:

# <property_1>: <value_1> <property_2>:<value_2> => <variable_name> 

For example:

export fn main:
  # name: "Hussain" age:19 => information
  console.log information
  console.log information.name
  console.log information.age

This code block creates a hash map called information that has two properties: name and age. It then logs out the value of the information object and its individual properties. Here’s what it looks like:

We are now done with this section.

Conclusion

Although Clio is still in beta at the time of this writing, it has decent syntax usage that encourages clean code. Moreover, the fact that it supports multi-threaded operations by default means that will be a viable candidate for performance-critical applications in the future.

Clio seems to be a promising programming language, and I hope that the development team releases a stable build in the near future so that it can be used in production environments.

Thank you so much for reading!