`uranus`

uranus is a language built by following the book 'Writing a Interpreter in Go.'. More information can be found inside book, but general introduction is provided here.

Example Code

Statements end with ;.

Maths

(5 + 10 * 2 + 15 / 3) * 2 + -10

Booleans

(1 > 2) == false
!!false

If statements

if (1 < 2) { 10 } else { 20 }

Variable Assignment

let a = 5; let b = a; let c = b + a + 5; c;

Functions

let add = fn(x,y) { x + y;}; add(1,4)

Including closures.

let newAdder = fn(x) {
    fn(y) { x + y };
};

let addTwo = newAdder(2);

Strings

Language Features

Currently the language supports

Variables
Booleans
Integers
Functions (Including higher-order function and closures.)
Strings
Assignment statements
Return Statements

Interpreter Features

It has a custom built lexer. Along with a Pratt Parser. The evaluator is a tree-walking evaluator.

Code Structure

The code is structured with 6 major parts.

AST
Lexer
Token
Parser
Object
Evaluator

Token

This package defines what kind of symbols are used in uranus. It also defines the type of INTEGERS and BOOLEANS.

Lexer

This package separates the input into a stream of tokens according to the rules defined in the token package.

AST

These are the rules of the language, this package defines the structure of each expression found in uranus.

Parser

This package parses the tokens in into a IR, according to the rules defined by the ast package.

Object

The language's internal object system. This does not mean the language is object-oriented. It simply means internally a structure for encapsulation each value is used.

Evaluator

This package contains the all-important eval function. Which takes any Node and parses returning a value.

Testing

All the tests are written alongside the code itself. To test the code use

make test

pspiagicw/uranus

uranus