mustBeArray

mustBeArray.js

/*
e.g.
mustBeArray([123, 456, 789]) => [123, 456, 789]
mustBeArray(123) => [123]
*/
const mustBeArray = R.unless(R.is(Array), R.of);

// array type expected
function doSomething (numbers) {
  // ...
  console.log(numbers);
  // ...
}

doSomething(mustBeArray(123));
// => [123]

doSomething(mustBeArray([123, 456]));
// => [123, 456]

function saveUsers (users) {
  // ...
  console.log(users);
  // ...
}

Promise.resolve({ name: 'haru', age: 1 }).then(mustBeArray).then(saveUsers);
// => [{ name: 'haru', age: 1 }]