DmitrySoshnikov

<?php

require('CalcParser.php');

var_dump(CalcParser::parse('2 + 2 * 2'));

/*

Result:

DmitrySoshnikov

/**
 * Calculator grammar for a parser in Python.
 *
 * syntax-cli -g calculator.ast.php.js -m LALR1 -o CalcParser.php
 *
 * <?php
 *
 *   require('CalcParser.php');
 *   var_dump(CalcParser::parse('2 + 2 * 2'));
 */

DmitrySoshnikov

const CalcParser = require('./CalcParser.js');

console.log(CalcParser.parse('2 + 2 * 2')); // AST
/*

Result:

  {
    type: "Binary",
    left: {

DmitrySoshnikov

/**
 * Calculator grammar for a parser in JavaScript.
 *
 * syntax-cli -g calculator.ast.js -m LALR1 -o CalcParser.js
 *
 * const CalcParser = require('./CalcParser.js');
 * console.log(CalcParser.parse('2 + 2 * 2')); // AST
 */

{

DmitrySoshnikov

import calcparser

print(calcparser.parse('2 + 2 * 2')) # int(6)

DmitrySoshnikov

/**
 * Calculator grammar for a parser in Python.
 *
 * syntax-cli -g calculator.grammar.js -m LALR1 -o calcparser.py
 *
 * >>> import calcparser
 * >>> calcparser.parse('2 + 2 * 2')
 * >>> 6
 */

DmitrySoshnikov

class Foo {
  get x() {}
  set x(v) {}
}

class Bar extends Foo {
  x = 42;
}

console.log(new Bar().x); // undefined, should be 42

DmitrySoshnikov

/**
 * JS scoping, and this property resolutions rules in ES7/ES8.
 *
 * Quiz: x is gone, and x is everywhere!
 *
 * Help find Xs! What's the output?
 */ 

let x = 1;

DmitrySoshnikov

/**
 * Reverse indices of Lists/Arrays in ES6.
 *
 * by Dmitry Soshnikov <[email protected]>
 * MIT Style License
 */

'use strict';

class List extends Array {

DmitrySoshnikov

"Everything is an expression"... since ES1?

Many languages support "expression-only" semantics, allowing to use any construct in an expression position.

NOTE: the difference between expressions and statements is that the former produce a value, while the later don't.

For example, Ruby's if-expression:

x = 10