https://github.com/keyz/the-super-tiny-interpreter

Let's explain what a closure is by writing a JavaScript interpreter in JavaScript.
https://github.com/keyz/the-super-tiny-interpreter

Last synced: 2 months ago
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Let's explain what a closure is by writing a JavaScript interpreter in JavaScript.

• Host: GitHub
• URL: https://github.com/keyz/the-super-tiny-interpreter
• Owner: keyz
• License: mit
• Created: 2016-04-12T16:20:08.000Z (about 8 years ago)
• Default Branch: master
• Last Pushed: 2016-08-03T10:03:45.000Z (almost 8 years ago)
• Last Synced: 2024-04-16T21:05:09.797Z (2 months ago)
• Language: JavaScript
• Homepage: https://tonicdev.com/npm/the-super-tiny-interpreter
• Size: 38.1 KB
• Stars: 158
• Watchers: 5
• Forks: 16
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Lists

• build-your-own-x - **JavaScript**: _The Super Tiny Interpreter_

README

        
# The Super Tiny _Interpreter_

[![build status](https://img.shields.io/travis/keyanzhang/the-super-tiny-interpreter/master.svg?style=flat-square)](https://travis-ci.org/keyanzhang/the-super-tiny-interpreter)

[![test coverage](https://img.shields.io/coveralls/keyanzhang/the-super-tiny-interpreter/master.svg?style=flat-square)](https://coveralls.io/github/keyanzhang/the-super-tiny-interpreter?branch=master)

Let's explain what a **[closure](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Closures)** is by writing a JavaScript interpreter in JavaScript.

Try it here: https://tonicdev.com/npm/the-super-tiny-interpreter

This project is still a **work in progress**, but feel free to poke around and check out the unit tests.

## Disclaimer

The goal of this project is **not** to make a spec-compliant or blazing-fast interpreter. The goal, however, is to interpret a tiny subset of JavaScript features in **super-easy-to-read™** code.

## Supported Syntax

1. Numbers, Booleans, `null`, and `undefined`

  ```javascript

  12 // Numeric Literal

  true // Boolean Literal

  null // Null Literal

  undefined // Do you know that `undefined` is actually an identifier? Paul Irish calls shadowing it the "Asshole Effect".

  ```

2. Variable, a.k.a. Identifier

  ```javascript

  foo

  ```

3. Binary Operators

  ```javascript

  +, -, *, /, ==, ===, !=, !==, <, <=, >, >=

  ```

4. Unary Operators

  ```javascript

  !, -

  ```

5. Conditional Expression, a.k.a. the ternary operator

  ```javascript

  test ? consequent : alternate

  ```

6. Arrow Function Expression

  - Notice that we didn't implement the traditional `function` syntax. Arrow functions FTW!

  ```javascript

  (x) => x + 1

  (x) => {

    const y = x + 100;

    return y * y;

  }

  ```

7. Call Expression

  ```javascript

  foo(1, 2, 3)

  ```

8. Variable Declaration Statement

  - Notice that we only support `const` for now and there's NO mutation (assignment) in our language.

    - That means we can initialize stuff once and only once

    - And of course `const foo;` is not valid JavaScript

  - If you are familiar with Scheme/OCaml, then `const LHS = RHS` behaves just like a `letrec`.

  ```javascript

  const foo = 12;

  const fact = (x) => x < 2 ? 1 : x * fact(x - 1);

  ```