run-option.ts

import { isNone, Option, none, some } from 'fp-ts/lib/Option';

function runOption<T>(th: () => Iterator<Option<T>, Option<T>, unknown>): Option<T> {
    const iter = th();
    const go = (
        { done, value: v }: IteratorResult<Option<T>, Option<T>>,
    ): Option<T> => (done || isNone(v) ? v : go(iter.next(v.value)));

    return go(iter.next());
}

function* th() {
    /*
    option.chain(some(3), x =>
        option.chain(some(5), y =>
            some(x + y)))
    */
    const x = yield some(3);
    const y = yield some(5);
    return some(x + y);
}

function* th2() {
    const x = yield some(7);
    yield none;
    return some(x + 5);
}

console.log(runOption(th)); // { _tag: 'Some', value: 17 }
console.log(runOption(th2)); // { _tag: 'None' }