WaldoJeffers

// SUBJECT
// Write a function withParamTransform which,
// for any function f,
// for any parameter transformation such as (a, b, c) => (a, c, b) (inverting 2 parameters)
// satisfies the following condition:
withParamTransform(f)[(a, b, c) => (a, c, b)](1, 2, 3) === f(1, 3, 2)

// A more realistic example
const minus = (a, b) => a - b
minus(5, 2) === 3 // true

WaldoJeffers

import { renderNothing, lifecycle } from 'recompose';

/**
 * HOC to navigate to a dynamically computed route name
 * React Navigation does currently not accept a function to determine
 * the initial route at runtime
 */
const withDynamicInitialRouteName = Navigator => (screens, config = {}) => {
  if (typeof config.initialRouteName === 'function') {
    const getInitialRouteName = config.initialRouteName;

WaldoJeffers

import { compose, get, mergeWith, reduce } from 'conductor'

const character_ids = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
const fetchJSON = url => fetch(url).then(res => res.json())
const fetchCharacter = id => fetchJSON(`https://swapi.co/api/people/${id}`)
const getHomeworldName = compose(get('name'), fetchJSON, get('homeworld'), fetchCharacter)
const toObj = (key, value) => ({ [key]: value })
const countOne = name => toObj(name, 1)
const countHomeworld = compose(countOne, getHomeworldName)
const mergeByAdding = mergeWith(add)

WaldoJeffers

import { filter } from 'conductor'

const obj = { books: 10, ruler: 1, pencils: 5 }
const isEven = x => Promise.resolve(x % 2 === 0)
const result = await filter(isEven, obj) // { books: 10 }

WaldoJeffers

const obj = { books: 10, ruler: 1, pencils: 5 }
const isEven = x => Promise.resolve(x % 2 === 0)
const result = await Promise
  .all(Object.values(obj).map(isEven))
  .then(results => Object.keys(obj).reduce((acc, key, index) => {
    if (results[index]){
      acc[key] = obj[key]
    }
    return acc
  }, {}) // { books: 10 }

WaldoJeffers

import { filter } from 'conductor'

const numbers = [3, 1, 4]
const isEven = x => Promise.resolve(x % 2 === 0)
const result = await filter(isEven, numbers) // [4]

WaldoJeffers

const numbers = [3, 1, 4]
const isEven = x => Promise.resolve(x => x % 2 === 0)
const result = await Promise
  .all(numbers.map(isEven)))
  .then(results => numbers.filter((_, index) => results[index]))
  // [4]

WaldoJeffers

const obj = { books: 10, ruler: 1, pencils: 5 }
const add = (a, b) => a + b
const total = Object.values(obj).reduce(add, 0) // 16

WaldoJeffers

const obj = { books: 10, ruler: 1, pencils: 5 }
const isEven = x => Promise.resolve(x % 2 === 0)

WaldoJeffers

const result = await Promise
  .all(numbers.map(isEven)))
  .then(results => numbers.filter((_, index) => results[index]))
  // [4]