LangLang

"The progressive development of man is vitally dependent on invention." Nikola Tesla

Get started with LangLang

How run the interpreter

After cloning this repository on your computer, run the prompt below to generate the interpreter build.

g++ -g -std=c++20 $(find src/ -type f -name "*.cpp") -o langlang.out
./langlang.out <langlang_file>

How run tests

g++ -I../googletest/googletest/include -I../googletest/googletest \
    -L../googletest/build/lib -lgtest -lgtest_main -pthread \
    $(find tests/ -type f -name "*.cpp") $(find src/*/ -type f -name "*.cpp") -o run_tests.out && ./run_tests.out
./run_tests.out

1. Introduction

LangLang is an object-oriented programming language with robust features such as higher-order functions, conditional structures, loops, class support, and inheritance. It is designed to be expressive and easy to use, with built-in input (<<) and output (>>) capabilities for direct terminal interaction.

Hello, World!

Copy and run the file below to have your first contact with LangLang

>> "Hello, World!";

Run with the command:

./langlang.out hello.ll

2. Basic Syntax

2.1 Variable Declaration

In LangLang, variables are declared using var, followed by the variable name, its type, and an initial value:

var x -> number := 5;
var name -> string := "John";

• ->: Defines the variable type.
• :=: Assigns an initial value.

2.2 Data Types

LangLang supports the following data types:

• number: Represents integers or floating-point numbers.
• string: Represents character strings.
• func: Represents functions.
• <identifier>: User-defined classes can also be used as types.

2.3 Comments

LangLang supports comments using the following syntax:

<> This is a comment

3. Conditional Structures

LangLang supports conditional structures using the if-else syntax:

if (condition) {
  // code block
} else {
  // alternative block
}

Example:

if (10%3 == 1) {
  >> "Yes";
} else {
  >> "No";
}

4. Loops

LangLang supports both while and for loops for repeating blocks of code.

4.1 while Loop

The while loop repeats a block of code as long as a condition is true:

while (x > 0) { 
	>> x;
	x := x - 1;
}

4.2 for Loop

The for loop in LangLang is used to iterate over a range of values. Its syntax is:

for (var i -> number := start_value; i < end_value; i := i + step_value) {
  // code block
}

• start_value: Initial value of the loop variable.
• end_value: Condition to terminate the loop.
• step_value: Value by which the loop variable is incremented each iteration.

5. Functions

LangLang allows the creation of functions using the func keyword:

func function_name() -> return_type {
  // function body
  // return <value>
}

Example:

func counter() -> func -> void {
  var i -> number := 0;
  func count() -> void {
    i := i + 1;
    >> i;
  }
  return count;
}

5.1 Higher-Order Functions

Functions can return other functions, allowing a functional programming style:

var cc -> func -> void := counter();
cc();

6. Classes and Objects

LangLang is an object-oriented language, supporting the creation of classes and instances:

6.1 Class Definition

Classes are defined using the class keyword:

class person {
  var age -> number := 12;
  var name -> string := "John";

  func print() -> void {
    >> "Hello, I am" >> name;
  }
}

6.2 Class Instance

To create an instance of a class:

var p -> person := person();
p.print();

6.3 Inheritance

LangLang supports inheritance between classes. A child class inherits the properties and methods of the parent class:

class student : person {
  var code -> number;
  
  func print() -> void {
    >> "Hi, I am a student, my name is" >> name;
  }
}

7. Input and Output

LangLang has built-in support for input with << and output with >>:

>> "Enter your name:";
<< name;