typescript-monads/maybe/maybe.factory.js

Write cleaner TypeScript

var __values = (this && this.__values) || function(o) {
    var s = typeof Symbol === "function" && Symbol.iterator, m = s && o[s], i = 0;
    if (m) return m.call(o);
    if (o && typeof o.length === "number") return {
        next: function () {
            if (o && i >= o.length) o = void 0;
            return { value: o && o[i++], done: !o };
        }
    };
    throw new TypeError(s ? "Object is not iterable." : "Symbol.iterator is not defined.");
};
import { Maybe } from './maybe';
export function maybe(value) {
    return new Maybe(value);
}
export function none() {
    return Maybe.none();
}
export function some(value) {
    return maybe(value);
}
/**
 * Creates a function that returns a Maybe for the given property path.
 *
 * This is a powerful utility for safely navigating nested object structures.
 * It creates a type-safe property accessor function that returns a Maybe
 * containing the value at the specified path if it exists, or None if any
 * part of the path is missing.
 *
 * @param path A dot-separated string path to the desired property
 * @returns A function that takes an object and returns a Maybe of the property value
 *
 * @example
 * const getEmail = maybeProps<User>('profile.contact.email');
 *
 * // Later in code
 * const emailMaybe = getEmail(user);
 * // Returns Some(email) if user.profile.contact.email exists
 * // Returns None if any part of the path is undefined/null
 *
 * // Use with filter
 * const validEmail = getEmail(user).filter(email => email.includes('@'));
 *
 * // Use with match
 * getEmail(user).match({
 *   some: email => sendVerification(email),
 *   none: () => showEmailPrompt()
 * });
 */
export function maybeProps(path) {
    var segments = path.split('.');
    return function (obj) {
        var e_1, _a;
        var current = obj;
        try {
            for (var segments_1 = __values(segments), segments_1_1 = segments_1.next(); !segments_1_1.done; segments_1_1 = segments_1.next()) {
                var segment = segments_1_1.value;
                if (current === null || current === undefined || !(segment in current)) {
                    return none();
                }
                current = current[segment];
            }
        }
        catch (e_1_1) { e_1 = { error: e_1_1 }; }
        finally {
            try {
                if (segments_1_1 && !segments_1_1.done && (_a = segments_1.return)) _a.call(segments_1);
            }
            finally { if (e_1) throw e_1.error; }
        }
        return maybe(current);
    };
}
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