baby-interpreter

README

Baby is a small, functional-based programming language

Think of simplified version of JavaScript with a more welcoming syntax all while limiting ambiguity and providing powerful built-in features. The interpreter is heavily influenced by the one built in Thorsten Ball's books(Monkey) but it aims to extend the language by providing various enhancements such as different levels of assignment(deep-copy, shallow-copy etc), operators, and a wider array of built-in functionality. (while loops, doWhile, etc)

Below is a functional implementation of MergeSort in Baby.

Functional MergeSort in Baby

let funcMS = fun(cmp, x, y) {
	if (isEmpty(x) & (!isEmpty(y))) {
		return y;
	}
	if ((!isEmpty(x)) & isEmpty(y)) {
		return x;
	}

	let result = [];
	if (cmp(head(x), head(y))) {
		result = append(result, head(x));
		result = append(result, funcMS(cmp, rest(x), y));
	} else {
		result = append(result, head(y));
		result = append(result, funcMS(cmp, x, rest(y)));
	};
	return result;
};

let split = fun(x, y, z) {
	let parts = [0,1];
	if (isEmpty(x)) {
		parts = insert(parts, y, 0);
		parts = insert(parts, z, 1);
		return parts;
	} else {
		return split(rest(x), z, append(head(x),y));
	};
};

let mergesort = fun(cmp, x) {
	if (isEmpty(x) | isEmpty(rest(x))) {
		return x;
	} else {
		let parts = split(x, [], []);
		return funcMS(cmp, mergesort(cmp, get(parts, 0)), mergesort(cmp, get(parts, 1)));
	};
};

mergesort(fun(x,y) { return (x<y);}, [12, 11, 13, 5, 6, 7]) =*= [5,6,7,11,12,13];

• Baby is small. The Interpreter implementation is around 3,500 lines. Making it understandable and maintainable.

• Baby is reasonably fast. For an interpreted language, Baby is reasonably fast. With GO being the host language, it makes use of GoLang's performant Garbage Collector and speedy memory allocation.

• Baby encourages declarative programming. Imperative programming can be confusing to beginners. Baby aims to clear the confusion by providing a declarative safe space while providing imperative tools so everyone is happy. :)

If you like the sound of this? You can even try it in your browser!

Language Tour

Baby's syntax is designed to be familiar to people coming from JavaScript-like languages while being a lot simpler.

Code is stored in plain text files with a .bb file extension. Baby is an interpreted language and is not compiled

Reserved words

Here are the reserved keywords in Baby:

fun
let
if
else
while
return

Operators

Other than the expected operators that are included in most programming languages, Baby throws some new operators to the mix:

Special Equality Operators

Reference Equality

Evaluating whether references are identical is denoted by the infix operator =&=.

Likewise, reference inequality is denoted by !&=.

Value Equality

Evaluating whether values at addresses are identical is denoted by the infix operator =*=.

Likewise, value inequality is denoted by !*=.

Special Assignment Operators

Reference Assignment

In Baby, making a deep copy is simple. In this case, after assignment both the value and the address are assigned. In Baby this is denoted by the =& infix operator.

  b =& a // Shallow copy (assign the value and the reference)
  b =&= a ----> true
  b =\*= a ----> true

Value Assignment

In Baby, making a deep copy is simple. In this case, deep copy entails that after assignment only the value is assigned not the address. In Baby this is denoted by the =* infix operator and can be inferred with the = infix operator.

Here is an example:

  b =* a // Deep copy (simply take the value)
  b =&= a ----> false
  b =*= a ----> true

Identifiers

Identifiers must be composed of letters and can contain underscores. CamelCase or kebab-case are encouraged. Case is sensitive. Numbers in identifiers(ex: foo3) are not supported.

hi
camelCase
PascalCase
_under_score
ALL_CAPS

Blocks

While Loops

While loops are implements just as most other programming languages:

while (<condition>) {<consequence>}

Do while Loops

Do while loops are a little trickier: first, a function that returns a boolean entailing the condition of the loop should be defined. The body of this function will be the body of the loop. Then a call is made to the built-in doWhile function which does all the magic.

let i = 6;
let inc = fun() {i=i+1; return (i<5)};
doWhile(inc);
print(i); // 7

If-Else statements

If-Else statement are structured like so: if (<condition>) <consequence> else <alternative>

Functions

Functions are declared like so : let <identifier> = fun(<list of params(identifiers) {<list of statements>}

Baby supports closures as well as the passing of functions(higher-order functions). The return keyword can be omitted but is recommended for code readability.

Declaration Statements

Initial Assignment is done with let like so: let <identifier> = <expression>. In re-assignment let can be omitted like so <identifier> = <expression>.