Avaq

Algebraic Law Cheatsheet

An overview of algebraic laws from the perspective of a functional programmer. I've used a Haskell-esque syntax for the definitions of the laws and examples.

General Laws

name	definition	example
Identity [¹][]	f x = x	add 0 42 = 42

Avaq

-- Create our directories table.
CREATE TABLE `directories` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `name` varchar(255) DEFAULT NULL,
  `lft` int(11) NOT NULL,
  `rgt` int(11) NOT NULL,
  PRIMARY KEY (`id`),
  UNIQUE KEY `directory_lft` (`lft`),
  UNIQUE KEY `directory_rgt` (`rgt`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8;

davidchambers

Challenge

Write a function of type String -> Integer. The input may or may not be a valid JSON string. If it is valid, the resulting JavaScript value is expected to be an object, but may not be. If it is an object, it is expected to have a foo property whose value is expected to be an object, but may not be. This value is expected to have a bar property which is expected to be an object with a baz property whose value is expected to be an array of strings. Each of these strings is expected to be a hex representation of an integer (e.g. 0xFF). If every element of the array meets this expectation, the

olih

Processing JSON using jq

jq is useful to slice, filter, map and transform structured json data.

Installing jq

On Mac OS

brew install jq

DrBoolean

const daggy = require('daggy')
const Task = require('data.task')
const _ = require('lodash')
const kleisli_comp = (f, g) => x => f(x).chain(g)
const compose = (f, g) => x => f(g(x))
const id = x => x

//=============FREE=============
const Free = daggy.taggedSum({Impure: ['x', 'f'], Pure: ['x']})
const {Impure, Pure} = Free

DrBoolean

const daggy = require('daggy')
const compose = (f, g) => x => f(g(x))
const id = x => x

//===============Define Coyoneda=========
const Coyoneda = daggy.tagged('x', 'f')

Coyoneda.prototype.map = function(f) {
  return Coyoneda(this.x, compose(f, this.f))
}

DrBoolean

const daggy = require('daggy')

const compose = (f, g) => x => f(g(x))
const id = x => x
const kleisli_comp = (f, g) => x => f(x).chain(g)

//=============FREE=============
const Free = daggy.taggedSum({Impure: ['x', 'f'], Pure: ['x']})
const {Impure, Pure} = Free

Avaq

const I  = x => x
const K  = x => y => x
const A  = f => x => f (x)
const T  = x => f => f (x)
const W  = f => x => f (x) (x)
const C  = f => y => x => f (x) (y)
const B  = f => g => x => f (g (x))
const S  = f => g => x => f (x) (g (x))
const S_ = f => g => x => f (g (x)) (x)
const S2 = f => g => h => x => f (g (x)) (h (x))

joepie91

Don't use VPN services.

No, seriously, don't. You're probably reading this because you've asked what VPN service to use, and this is the answer.

Note: The content in this post does not apply to using VPN for their intended purpose; that is, as a virtual private (internal) network. It only applies to using it as a glorified proxy, which is what every third-party "VPN provider" does.

• A Russian translation of this article can be found here, contributed by Timur Demin.
• A Turkish translation can be found here, contributed by agyild.
• There's also this article about VPN services, which is honestly better written (and has more cat pictures!) than my article.

imjasonh

* {
    font-size: 12pt;
    font-family: monospace;
    font-weight: normal;
    font-style: normal;
    text-decoration: none;
    color: black;
    cursor: default;
}