retry-ts/es6/Task.js

Retry combinators for monadic actions that may fail

/**
 * @since 0.1.0
 */
import * as T from 'fp-ts/es6/Task';
import * as O from 'fp-ts/es6/Option';
import { pipe } from 'fp-ts/es6/pipeable';
import { applyPolicy, defaultRetryStatus } from '.';
/**
 * Apply policy and delay by its amount if it results in a retry.
 * Returns updated status.
 *
 * @since 0.1.0
 */
export function applyAndDelay(policy, status) {
    var newStatus = applyPolicy(policy, status);
    return pipe(newStatus.previousDelay, O.fold(function () { return T.task.of(newStatus); }, function (millis) { return T.delay(millis)(T.task.of(newStatus)); }));
}
/**
 * Retry combinator for actions that don't raise exceptions, but
 * signal in their type the outcome has failed. Examples are the
 * `Option`, `Either` and `EitherT` monads.
 *
 * @since 0.1.0
 */
export function retrying(policy, action, check) {
    var go = function (status) {
        return pipe(status, action, T.chain(function (a) {
            if (check(a)) {
                return pipe(applyAndDelay(policy, status), T.chain(function (status) {
                    return pipe(status.previousDelay, O.fold(function () { return T.task.of(a); }, function () { return go(status); }));
                }));
            }
            else {
                return T.task.of(a);
            }
        }));
    };
    return go(defaultRetryStatus);
}