Async example

Quote from https://jaredforsyth.com/2017/06/23/when-will-reasonml-be-ready/:

> The OCaml community has some pretty fundamental fragmentations (there are three incompatible versions of the standard library, two incompatible ways to handle async), and documentation is generally pretty sparse. We’re hoping to establish good “batteries included” standard library (that will work for both js and native), but it will take some time.

To JS programmers, async pattern is very common nowadays, we are get used to it. Hence, been said that "there is no standard for async pattern in OCaml" made me worried how to convert my async codes into Reason counterpart.

It would be nice if there is a tutorial about how to do so in OCaml. (e.g. extend the Todo app to send the new item to a simple backend server)

Use o artigo vinculado e o exemplo do aplicativo Todo como pontos de partida; primeiro identifique o padrão async e como o aplicativo deve enviar um novo item para um backend. Considera-se concluído quando houver um tutorial explicando esse fluxo para leitores de Reason/OCaml e JavaScript, com etapas suficientes para acompanhá-lo.

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