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x/ramda/otherwise.js

:ram: Practical functional Javascript
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import _curry2 from './internal/_curry2';import _assertPromise from './internal/_assertPromise';

/** * Returns the result of applying the onFailure function to the value inside * a failed promise. This is useful for handling rejected promises * inside function compositions. * * @func * @memberOf R * @since v0.26.0 * @category Function * @sig (e -> b) -> (Promise e a) -> (Promise e b) * @sig (e -> (Promise f b)) -> (Promise e a) -> (Promise f b) * @param {Function} onFailure The function to apply. Can return a value or a promise of a value. * @param {Promise} p * @return {Promise} The result of calling `p.then(null, onFailure)` * @see R.then * @example * * var failedFetch = (id) => Promise.reject('bad ID'); * var useDefault = () => ({ firstName: 'Bob', lastName: 'Loblaw' }) * * //recoverFromFailure :: String -> Promise ({firstName, lastName}) * var recoverFromFailure = R.pipe( * failedFetch, * R.otherwise(useDefault), * R.then(R.pick(['firstName', 'lastName'])), * ); * recoverFromFailure(12345).then(console.log) */var otherwise = _curry2(function otherwise(f, p) { _assertPromise('otherwise', p);
return p.then(null, f);});export default otherwise;