skrishnan2001/coding-an-interpreter

Oak-Programming-Language - A small programming language

Oak-Programming-Language

A small programming language created by Clement Mihailescu & Hussein Farah

Overview

Oak is a small language that Clement and Hussein built over the course of a four-day hackathon. It supports various fundamental programming concepts such as variable-declaration, function calling, conditional statements, loops, proper order of operations, and recursion. The language syntax is meant to be very readable and intuitive: for instance, every function body, conditional statement body, and loop body is wrapped in colons; loops follow a "from [startingNumber] to [endingNumber] with [variable]" syntax; and variable types are specified upon declaration. Below is the language's EBNF-based grammar, and following that are some examples of programs that the language can run. Even further down is a link to a repl.it where the programs can be run.

Grammar

program::= variable-declaration | conditional | loop | expression [ program ]

variable-declaration::= variable-keyword variable-name assignment-operator variable-body
variable-keyword::= "fn" | "num" | "str" | "arr" | "bool"
variable-name::= identifier
assignment-operator::= "="
variable-body::= function-declaration | expression | comparison

function-declaration::= function-arguments wrapper function-body wrapper
function-arguments::= "(" [ { expression "," } ] ")"
function-body::= program

conditional::= "if" comparison wrapper program wrapper [ { "else if" ... } | "else" wrapper program wrapper ]

comparison::= expression [ comparison-operator expression ]
comparison-operator::= "=="

loop::= "from" expression "to" expression "with" identifier wrapper program wrapper

expression::= term { "+" | "-" term }
term::= factor { "*" | "/" | "%" factor }
factor::= number | string | boolean | array | identifier | "-" factor | "(" expression ")" | function-call
function-call::= identifier "(" [ { expression "," } ] ")"
identifier::= { letter }
number::= { digit } [ "." { digit } ]
string::= """ [ { * } ] """
array::= "[" [ { expression "," } ] "]"
boolean::= "true" | "false"

letter::= "a" | "b" | ... | "y" | "z" | "A" | "B" | ... | "Y" | "Z"
digit::= "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9"

wrapper::= ":"

Examples of Working Programs

Interpreter Instantiation

let Oak = new Interpreter(memory)

Basic Variable Declaration

Oak.input(`

	num one = 1
	num three = 3
	str hello = "hello"
	arr array = [1, 2, 3, 4, 5, 6, 7]
	fn add = (num a, num b) :
		=> a + b
	:
	fn echo = (num a) :
		=> a
	:
	
`)

Oak.memory

Basic Function Calling

Oak.input(`

	add(one, three) + add(echo(one), three)

`)

Basic Conditional Statements

Oak.input(`

	if 3 == 3 :
		print("First!")
	: elsif echo(one) == 1 :
		print("Second!")
	: else :
		print("Third!")
	:

`)

Basic Loops

Oak.input(`

	from 0 to 6 with i :
		num currentIndexValue = index(array, i)
		print(currentIndexValue)
	:

`)

Nested Loops

Oak.input(`

	from 1 to 3 with i :
		from 1 to 3 with j :
			from 1 to 3 with k :
				print(i, j, k)
			:
		:
	:

`)

FizzBuzz

Oak.input(`

	fn fizzBuzz = (num n) :
		from 1 to n with i :
			if i % 15 == 0 :
				print("FizzBuzz")
			: elsif i % 5 == 0 :
				print("Buzz")
			: elsif i % 3 == 0 :
				print("Fizz")
			: else :
				print(i)
			:
		:
	:

`)

Oak.input(`

	fizzBuzz(35)

`)

Recursion and Fibonacci

Oak.input(`

	fn fib = (num n) :
		if n == 1 :
			=> 0
		: elsif n == 2 :
			=> 1
		: else :
			=> fib(n - 1) + fib(n - 2)
		:
	:

`)

Oak.input(`

	from 1 to 15 with i :
		print(i, fib(i))
	:

`)

Order of Operations

Oak.input(`

	fn alwaysTwo = (num n) :
		=> ((((n + 47 % (19 * add(-3, 5))) * echo(three - one) - 4) / fib(4) - n + fib(echo(10)) - 29) * 3 - 9) / 3 - (((n + 109 % 10) * 2 - 4) / 2 - n)
	:

`)

Oak.input(`

	alwaysTwo(4751)

`)

Repl.it Link

https://repl.it/ETv1/561