Isolating the impurity of randomness in card games - Examples

a-deck.js

const thisIsADeck = [
  'this is a card',
  3464562456, // this is also a card,
  { attack: `i'm a property of a card!` }, // another card
  [
   `I'm an element inside a card.`,
   `I'm not a card because I'm not in the root level`,
   `The card in this case is the whole array containing these phrases`,
  ],
]

another-deck.js

const deck = [
  { name: 'Fireball', damage: 6, cost: 2 },
  { name: 'Thunderstorm', damage: 10, cost: 3 },
  { name: 'Ice Razors', damage: 30, cost: 7 },
]

card-and-deck.js

const { without } = require('ramda')
const card = deck[0] // 1. Card
const newDeck = without([card], deck) // 2. Remaining deck

curried-draw-from-top.js

const { head } = require('ramda')
const drawFromTop = draw(head)
const { card, newDeck } = drawFromTop(deck)

curried-draw.js

const draw = curry((cardPicker, deck) => {
  const card = cardPicker(deck)
  const newDeck = without(card, deck)
  return { card, newDeck }
})

deck-fiddling.js

// http://ramdajs.com/docs/#pipe
const { pipe, curry } = require('ramda')

const addToTop = curry((card, deck) => [card, ...deck])

const addToBottom = curry((card, deck) => [...deck, card])

const addBoth = pipe(
  addToTop({ name: 'Ice Wall', damage: 3, cost: 1 }),
  addToBottom({ name: 'Earth Strike', damage: 6, cost: 3 })
)

const newDeck = addBoth(deck)

draw-from-the-bottom.js

const last = array => array[array.length - 1]
const { card, newDeck } = draw(last, deck)

draw-from-the-top.js

const head = array => array[0]
const { card, newDeck } = draw(head, deck)

draw.js

const draw = (cardPicker, deck) => {
  // 1. We want to know what card we drew
  const card = cardPicker(deck)
  // 2. We want the new deck after the draw
  const newDeck = without(card, deck)
  return { card, newDeck }
}

framework-hater.js

const without = (element, array) => array.filter(e => e !== element)
// Watch out because on this one the "element" is not an array like the Ramda function.

link.md

These are the examples used in this article

random-draw.js

const randomElement = array =>
  array[Math.floor(Math.random() * array.length)]

draw(randomElement, deck)

seeded-random.js

const seededRandom = seed => Math.abs(Math.sin(seed))

shuffle.js

const { pipe, sortBy, prop, pluck } = require('ramda')

const shuffle = (seed, deck) => {
  const routine = pipe(
    deck => deck.map((card, index) => ({
      rank: seededRandom(seed + index),
      card,
    })),
    sortBy(prop('rank')),
    pluck('card')
  )
  return routine(deck)
}

shufflin.js

const seed = 1234
const shuffledDeck = shuffle(seed, deck)