krzysztofczernek

// A version with explicit references to arguments
const getLastUserDisplayName = () => {
  return getAllUsers()
    .then(users => R.last(users))
    .then(lastUser => lastUser.firstName)
    .then(firstName => R.toUpper)
}

// A point-free equivalent
const getLastUserDisplayName = () => {

krzysztofczernek

// Traditional way, no composition
const activeProjectsDetails1 = projects => {
  const active = projects.filter(project => project.isActive)
  const detailsOnly = projects.map(project => pickProjectDetails(project))
  return orderBy(detailsOnly, ['updatedAt'])
}

// Composition
const activeProjectsDetails2 = projects => pipe(
  filter(isActive),

krzysztofczernek

const R = require('ramda')

const trace = value => {
  console.log(value)
  return value
}

const fastestCarPF = R.pipe(
  R.sortBy(R.prop('horsepower')),
  trace,

krzysztofczernek

const trace = value => {
  console.log(value)
  return value
}

krzysztofczernek

const R = require('ramda')

const fastestCarPF = R.pipe(
  R.sortBy(R.prop('horsepower')),
  R.last,
  R.prop('name')
)

krzysztofczernek

const R = require('ramda')

const fastestCar = cars => {
  const sorted = R.sortBy(car => car.horsepower, cars)
  console.log(sorted)
  const fastest = R.last(sorted)
  return fastest.name
}

krzysztofczernek

const R = require('ramda')

const fastestCar = cars => {
  const sorted = R.sortBy(car => car.horsepower, cars)
  const fastest = R.last(sorted)
  return fastest.name
}

krzysztofczernek

const selectedNames = users =>
  R.pipe(
    R.map(R.unary(parseInt)),
    R.map(R.flip(R.prop)(users)),
    R.map(R.prop('name'))
  )

krzysztofczernek

const selectedNames = users =>
  R.pipe(
    R.map(R.unary(parseInt)),
    R.map(userId => users[userId]),
    R.map(R.prop('name'))
  )

krzysztofczernek

const R = require('ramda')

const selectedNames = users => selectedUserIds => {
  return selectedUserIds
    .map(R.unary(parseInt))
    .map(userId => users[userId])
    .map(R.prop('name'))
}