qlang

About

This repository contains a complete interpreter for qlang, written in C++. qlang is a small imperative programming language with a simple syntax.

Grammar

qlang supports common programming concepts including weak static typing, variable declaration, function calling, conditional statements, loops and recursion. For a more detailed overview, checkout grammar.md.

Examples

A complete range of example programs written in qlang can be viewed in the examples folder.

$ cat hello_world.q

fn main none () start
    out "Hello, World!"
end

$ cat gcd.q

fn gcd num (num x, num y) start
    if y == 0 start
        return x
    end
    else start
        return gcd(y, x % y)
    end
end

fn main none () start
    num x
    num y

    in x
    in y
    out gcd(x, y)
end

$ cat fibonacci_iter.q

fn main none () start
    arr fib
    num n

    in n
    if n >= 0 start
        fib.push(0)
        fib.push(1)
        for i of range(2, n + 1) start
            fib.push(fib.at(i - 1) + fib.at(i - 2))
        end
        outl "fib[" + n + "] = " + fib.at(n)
        outl "fib[0..n] = " + fib
    end
    else start
        out "n must be >= 0"
    end
end

$ cat two_sum.q

fn two_sum arr (arr a, num target) start
  arr res
  num n
  map mp

  for i of range(0, a.len()) start
    n = a.at(i)
    if mp.find(n) start
      res.push(mp.at(n))
      res.push(i)
      return res
    end
    mp.at(target - n) = i
  end

  return res
end

Running locally

To try out qlang yourself, clone this repository first:

git clone https://github.com/malav-mehta/qlang.git

Compile the project using the Makefile:

cd qlang
make

All done! To run a program, go to the build directory:

cd build

Finally, you can run the executable. To interpret code located at path/to/file.q, run the following command:

./q /path/to/file.q

Testing

To test the program, run the following command from the root directory:

make test

Tech stack

• C++
• Bash