nullableToResult

Converts a nullable value to a Result. null and undefined map to Errors, any other value maps to Oks.

Signature

nullableToResult(a, givenFallback)

forall a, b:
  (a or None, b) => Result b a
& (a or None) => Result None a

Documentation

Converts a nullable value to a Result. null and undefined map to Errors, any other value maps to Oks.

A nullable is a value that may be any type, or null/undefined.

DEPRECATION WARNING:
In 2.0.x, nullableToResult took only one parameter. This form of the function is now deprecated in favour of passing an explicit fallback value.

Example:

const nullableToResult = require('folktale/conversions/nullable-to-result');
const { Error, Ok } = require('folktale/result');

nullableToResult(undefined, 'error');
// ==> Error('error')

nullableToResult(null, 'error');
// ==> Error('error')

nullableToResult(1, 'error');
// ==> Ok(1)

Properties

Source Code

Defined in source/conversions/nullable-to-result.js at line 24, column 0

function(a, givenFallback) {
  const oldBehaviour = arguments.length < 2;  // eslint-disable-line prefer-rest-params
  if (oldBehaviour) {
    deprecated(`nullableToResult(value) is being deprecated in favour of providing an explicit fallback value.
nullableToResult(value, fallback) is the new preferred form of this function.
`);
  }

  const fallback = oldBehaviour ? a : givenFallback;
  return a != null ?  Ok(a)
  :      /* else */   Error(fallback);
}