takeUnless

Conditionally unwraps and returns the inner value if the predicate is false, otherwise returns null.

Note that unlike .unless(), this method unwraps the Maybe<T> class, returning the inner value. As such, this method is not chainable.

import { maybe } from "@tsly/maybe";
 
function handleRequest(arg: number) {
    const resp: { ok: boolean, data: number[] } | undefined = loadSomething(arg);
 
    return maybe(resp)?.takeUnless(it => !it.ok);
}
 
function loadSomething(arg) {
    if (arg == 0) return undefined;
 
    if (arg % 2 == 0) return { ok: true, data: [1, 2, 3] }
    else return { ok: false, data: []  }
}
 
console.log(handleRequest(0)); // undefined
console.log(handleRequest(1)); // null
console.log(handleRequest(2)); // { ok: true, data: [1, 2, 3] }

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takeIf if