Added run function imitating "do-notation".

[zegerhoogeboom]

This PR adds a function called run that imitates Haskell's do-notation, as inspired by this blogpost. This implemented version here is slightly different to make it nicer-to-use. This implementation accepts returning Maybe<T> or just T from the generator function.

This example is also implemented as a unit test but for clarification, this PR adds the possibility to do the following:

const result: Maybe<number> = Maybe.run<number>(function* () {
  const x = yield Maybe.just(1);
  const y = yield Maybe.just("2");
  return x + parseInt(y);
});

Without the run function, this example could be solved using sequence or using a combination of .bind().map(), which doesn't scale in terms of indentation. Using sequence seems like an odd solution in this case as it's not particularly natural to represent these values in a map.

const result: Maybe<number> = Maybe.just(1).bind((x) => {
    return Maybe.just("2").map((y) => {
        return x + parseInt(y);
    })
});

Note though that the variables within the generator function (e.g. in above example const x) will be of type any, but any mixture of types within Maybe<T> is accepted (e.g. in above example Maybe<number> and Maybe<string>

[cbowdon]

Sorry this has languished so long. It's a neat idea, but I'm no longer actively maintaining this project and therefore not going to merge any more PRs. Thank you very much for your contribution all the same.

[zegerhoogeboom]

No worries, I'm still actively using the library, thanks for creating it!