Overview

Make Ari come alive¶

Once Ari is downloaded, either:
- double-click the file
  
  or
- open a command line in the same folder and enter ari-windows or ./ari-linux

Ari's interface should look like this

‾‾‾‾‾‾‾‾‾
Ari 0.1.0
_________

>

Interpreter mode¶

The above interface is called the interpreter mode or more commonly known as REPL.
Experiment with Ari by typing in Ari-compatible syntax:

Run a program¶

For most practical purposes, it is better to write an Ari program in a separate file.
For example, if the file's name is called even_numbers.ari, open the command line and enter ari-windows even_numbers.ari or ./ari-linux even_numbers.ari

Below is a sample code for even_numbers.ari and the result:

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for(let i = 0; i < 10; i = i + 2) {
    print i + ", ";
}

Placeholder

Values¶

Values are Ari's bread and butter:

1;               // Number
"Good mourning"; // String
true;            // Boolean
null;            // Null
[1, 2, 3];       // Array of Numbers
["abc", "def"]; // Array of Strings

Logical comparisons are also essential.
Check out the other sections for more info.

Semicolon¶

Never forget to add semicolons behind each statement. I know it is annoying, but consider it a mental discipline, like house chores.
1 2 3
1 + 2; 50 + 70 // Missing semicolon! 19 + 21;

Whitespace¶

Ari doesn't care about whitespace. How much spacing to use is up to you:

   3; 2;    2; 3;
   4;   1;1;   4;
    5;        5;
      6;    6;
        7;7;

"I love whitespace";

Comments¶

Everyone loves to gossip, so comment to your heart's content by adding double slashes, //:

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"Shoplifters will be prostituted";
// Note to self: Change this misspelling in one year's time when I review this code again.
// Just kidding.

Variables¶

The let keyword indicates the declaration of a new variable.

Variable names can only contain numbers, alphabets, and the underscore _. Also, names cannot begin with a number.

let a = 1;
a = 2;
a = 3 + a; // 5
let 3musketeers = 3; // Error because variable name starts with a number

Reserved keywords

class, super, and this are reserved for a future version of Ari which includes classes, so they are forbidden.

Block scoping and shadowing are extremely important concepts that are relevant in other languages.

Displaying output¶

print displays something in the command line:

let a = 10;
print "Item no. ";
print a;
// Output: Item no. 10

println adds a newline at the end of the output:

let a = 10;
println "Item no. ";
println a;
// Output: Item no.
//         10

If-Else¶

The typical if - else trope:

let a = "apple";
if (a == "banana") {
    println "banana";
}
else {
    println a; // This gets printed
}

Loops¶

While loops repeat as long the condition is true:

let a = 3;
while(a > 0) {
    println a;
    a = a - 1;
}
// 3
// 2
// 1

For loops simplify counter-like loops:

for(let a = 3; a > 0; a = a- 1) {
    println a;
}
// 3
// 2
// 1

There are also keywords like continue and break

Exiting the program prematurely¶

bai quits the program and prints a given value:

for(let a = 3; a > 0; a = a- 1) {
    println a;
    if(a == 2) {
        bai "i'm sick of loops.";
    }
}
// 3
// 2
// I'm sick of loops
// Program ends

Arrays¶

Arrays must contain the same type of elements.

Indexes start from 0.

let a = [1, 2, 3];  // Array of Numbers
let b = ["x", "y"]; // Array of Strings
a[1] = 5;
println a; // [1, 5, 3]
a[2] = b[1]; // Error because different types

Arithmetic for arrays of Numbers are straightforward:

let a = [1, 2, 3];
let b = [10, 20, 30];
println a + b; // [11, 22, 33]
println a * b; // [10, 40, 90]

map, filter and reduce are especially useful for quick array transformations.

Functions¶

Functions enable code reusability:

fn is_greater(input) {
    return input > 5;
}
println is_greater(1); // false
println is_greater(6); // true

Functions are first class citizens. What does this mean?
Closure is another important concept to grasp and is relevant to other languages.

Built-in Functions¶

Built-in functions are useful for executing common operations without reinventing the wheel.
There are built-in functions for Number, String and Array.
Other functions include:

More Examples¶

Go here