CFP - Docs - isLaden

isLaden

(collection: Collection | string) => boolean

Test if a collection or string is non-empty

Try It

isLaden([1]) // is true
isLaden([]) // is false

isLaden('a') // is true
isLaden('') // is false
isLaden([1]) // is true
isLaden([]) // is false

isLaden('a') // is true
isLaden('') // is false

Try It

isLaden([1]) // is true
isLaden([]) // is false

isLaden('a') // is true
isLaden('') // is false
isLaden([1]) // is true
isLaden([]) // is false

isLaden('a') // is true
isLaden('') // is false

Usually we can iterate over collections without worrying whether they contain elements. Sometimes, however, we need to treat non-empty collections differently. Below, we have appointments scheduled for the next week. To avoid a bunch of empty days in our display, let's only show those with appointments.

Try It

const appointments = {
  Monday: [],
  Tuesday: [
    {
      time: '8am-9:30',
      client: "Baz's Baby Furniture",
    },
    {
      time: '11am-12',
      client: 'University Of Florida',
    },
  ],
  Wednesday: [],
  Thursday: [],
  Friday: [
    {
      time: '9am-10',
      client: 'RVs R Us',
    },
  ],
}

const displayOneAppt = ({ time, client }) => {
  return `  At: ${time}\n` + `  With: ${client}`
}

const displayDayAppts = (appts, day) => {
  const dayAppts = appts.map(displayOneAppt).join('\n\n')
  return `${day}:\n` + dayAppts
}

const displayAllDayAppts = compose([
  keepWhen(isLaden),
  mapValues(displayDayAppts),
  joinValues('\n\n'),
])

const apptDisplay = displayAllDayAppts(appointments)
console.log(apptDisplay)
// prints
// Tuesday:
//   At: 8am-9:30
//   With: Baz's Baby Furniture
//
//   At: 11am-12
//   With: University Of Florida
//
// Friday:
//   At: 9am-10
//   With: RVs R Us
type Appointment = {
  time: string
  client: string
}
type Appointments = Record<string, Appointment[]>
const appointments: Appointments = {
  Monday: [],
  Tuesday: [
    {
      time: '8am-9:30',
      client: "Baz's Baby Furniture",
    },
    {
      time: '11am-12',
      client: 'University Of Florida',
    },
  ],
  Wednesday: [],
  Thursday: [],
  Friday: [
    {
      time: '9am-10',
      client: 'RVs R Us',
    },
  ],
}

const displayOneAppt = ({ time, client }: Appointment) => {
  return `  At: ${time}\n` + `  With: ${client}`
}

const displayDayAppts = (appts: Appointment[], day: string) => {
  const dayAppts = appts.map(displayOneAppt).join('\n\n')
  return `${day}:\n` + dayAppts
}

const displayAllDayAppts = compose([
  keepWhen(isLaden)<Appointments>,
  mapValues(displayDayAppts),
  joinValues('\n\n'),
])

const apptDisplay = displayAllDayAppts(appointments)
console.log(apptDisplay)
// prints
// Tuesday:
//   At: 8am-9:30
//   With: Baz's Baby Furniture
//
//   At: 11am-12
//   With: University Of Florida
//
// Friday:
//   At: 9am-10
//   With: RVs R Us

Try It

const appointments = {
  Monday: [],
  Tuesday: [
    {
      time: '8am-9:30',
      client: "Baz's Baby Furniture",
    },
    {
      time: '11am-12',
      client: 'University Of Florida',
    },
  ],
  Wednesday: [],
  Thursday: [],
  Friday: [
    {
      time: '9am-10',
      client: 'RVs R Us',
    },
  ],
}

const displayOneAppt = ({ time, client }) => {
  return `  At: ${time}\n` + `  With: ${client}`
}

const displayDayAppts = (appts, day) => {
  const dayAppts = appts
    .map(displayOneAppt)
    .join('\n\n')
  return `${day}:\n` + dayAppts
}

const displayAllDayAppts = compose([
  keepWhen(isLaden),
  mapValues(displayDayAppts),
  joinValues('\n\n'),
])

const apptDisplay =
  displayAllDayAppts(appointments)
console.log(apptDisplay)
// prints
// Tuesday:
//   At: 8am-9:30
//   With: Baz's Baby Furniture
//
//   At: 11am-12
//   With: University Of Florida
//
// Friday:
//   At: 9am-10
//   With: RVs R Us
type Appointment = {
  time: string
  client: string
}
type Appointments = Record<string, Appointment[]>
const appointments: Appointments = {
  Monday: [],
  Tuesday: [
    {
      time: '8am-9:30',
      client: "Baz's Baby Furniture",
    },
    {
      time: '11am-12',
      client: 'University Of Florida',
    },
  ],
  Wednesday: [],
  Thursday: [],
  Friday: [
    {
      time: '9am-10',
      client: 'RVs R Us',
    },
  ],
}

const displayOneAppt = ({
  time,
  client,
}: Appointment) => {
  return `  At: ${time}\n` + `  With: ${client}`
}

const displayDayAppts = (
  appts: Appointment[],
  day: string
) => {
  const dayAppts = appts
    .map(displayOneAppt)
    .join('\n\n')
  return `${day}:\n` + dayAppts
}

const displayAllDayAppts = compose([
  keepWhen(isLaden)<Appointments>,
  mapValues(displayDayAppts),
  joinValues('\n\n'),
])

const apptDisplay =
  displayAllDayAppts(appointments)
console.log(apptDisplay)
// prints
// Tuesday:
//   At: 8am-9:30
//   With: Baz's Baby Furniture
//
//   At: 11am-12
//   With: University Of Florida
//
// Friday:
//   At: 9am-10
//   With: RVs R Us

I understand "laden" is not a common term. It's the best I could find to convey a positive form of "non-empty" with the purpose of avoiding double negatives.