lwt VS ocaml-webmachine

> Also, didn't OCaml have weak support for concurrency? Has that changed recently?

OCaml has had Lwt for concurrent IO for long enough that it is now being deprecated in favor of Eio[1]:

https://github.com/ocsigen/lwt

[1] https://github.com/ocaml-multicore/eio

Here is link number 1 - Previous text "Lwt"

I have to admit I don't know much about ReScript and only have very basic exposure to OCAML, here is how you do await in it:

https://github.com/ocsigen/lwt

The `let* in` is a generic syntax for monads, it doesn't need a special one just for promise. This was in fact a debate back when async/await was in consideration for ECMAScript, but special syntax is hip so now we have `async/await` for Promise, `.?` for optionals and `flatMap` for arrays, basically the same thing.

Dream doesn't have much of a system call dependency footprint itself. It's basically just a convention for plugging request -> response functions into a web server. Some of its native dependencies will have to be replaced by Node equivalents. Soon after that, it would be portable to Node.

There is already work underway to port Dream to Mirage, to run in unikernels: https://github.com/aantron/dream/pull/22

Lwt, Dream's promise library, is itself getting ported to run on top of libuv: https://github.com/ocsigen/lwt/issues/813

libuv is, of course, the I/O library that powers Node, so it might be practical to run Dream as a native node module very soon after doing this.

(As an aside, I'm supposed to work on that libuv project, but instead I've been working on Dream :P)

We (a small company creating specialized inventory management and e-commerce systems) use Dream for web development. Webmachine and Cohttp for creating RESTful APIs. HTTP-clients with Ocurl and Cohttp. We are very happy with our choice of technologies.