Dream

Easy-to-use, feature-complete Web framework without boilerplate.

let hello who =
  <html>
  <body>
    <h1>Hello, <%s who %>!</h1>
  </body>
  </html>

let () =
  Dream.run
  @@ Dream.logger
  @@ Dream.router [
    Dream.get "/" (fun _ -> Dream.html (hello "world"));
  ]

Quick Start | Tutorial | Reference   

Dream is one flat module in one package, documented on one page, but with many examples. It offers:

• WebSockets and GraphQL for your modern Web apps.
• HTML templates with embedded OCaml or Reason — use existing skills!
• Sessions with pluggable storage back ends.
• Easy HTTPS and HTTP/2 support — Dream runs without a proxy.
• Helpers for secure cookies and CSRF-safe forms.
• Full-stack ML with clients compiled by Melange or js_of_ocaml.

...all without sacrificing ease of use — Dream has:

• A simple programming model — Web apps are just functions!
• Composable middleware and routes.
• Unified, internationalization-friendly error handling.
• Cryptography helpers, key rotation, and a chosen cipher.
• A neat logger, and attention to configuring the OCaml runtime nicely.
• Deployment instructions for Digital Ocean, Heroku, and Fly.io, with sample CI scripts.

Every part of the API is arranged to be easy to understand, use, and remember. Dream sticks to base OCaml types like string and list, introducing only a few types of its own — and some of those are just abbreviations for bare functions!

The neat interface is not a limitation. Everything is still configurable by a large number of optional arguments, and very loose coupling. Where necessary, Dream exposes the lower-level machinery that it is composed from. For example, the basic body and WebSocket readers return strings, but you can also do zero-copy streaming.

You can even run Dream as a quite bare abstraction over its underlying set of HTTP libraries, where it acts only as minimal glue code between their slightly different interfaces.

And, even though Dream is presented as one package for ordinary usage, it is internally factored into several sub-libraries, according to the different dependencies of each, for fast porting to different environments.

Dream is a low-level and unopinionated framework, and you can swap out its conveniences. For example, you can use TyXML with server-side JSX instead of Dream's built-in templates. You can bundle assets into a single Dream binary, or use Dream in a subcommand. Dream tries to be as functional as possible, touching global runtime state only lazily, when called into.

Quick start

The easiest way to use Dream is via opam. Install it and create a switch if you don't already have one. Then clone Dream and run the first tutorial example, 1-hello:

git clone https://github.com/camlworks/dream.git
cd dream/example/1-hello
opam install . --deps-only
dune exec --root . ./hello.exe

--root . makes the example directory the Dune project root, so dune builds only the example against the dream package installed by opam, rather than the Dream source in the surrounding checkout. If you're modifying Dream itself and want to observe the changes in the examples drop the --root ..

esy

Some examples, such as w-esy, show how to package a Dream application with esy.

Documentation

• Tutorial — Threads together the first several examples of Dream, touching all the basic topics, including security. See the full list and start wherever you like, or begin at 1-hello, the Dream version of Hello, world!
• Reason syntax — Several of the examples are written in Reason. See r-hello.
• Full-stack — See skeleton projects r-fullstack-melange and w-fullstack-jsoo.
• Deploying — Quick start instructions for small-to-medium deployments.
• Examples — These cover various HTTP scenarios.
• API reference
• Watching and live reloading.

Recommended projects

• dream-cli  —  command-line interface for Dream applications.
• dream-encoding  —   compression middleware.
• dream-livereload  —  live reloading.
• emile  —  email address syntax validation.
• letters  —  SMTP client.

Example repositories

• dream-mail-example  —  sends email using RabbitMQ and Mailgun [blog post, discuss].
• dream-melange-tea-tailwind  —  The Elm Architecture with a Dream server, client compiled by Melange.

Contact

Apart from the issues, good places to discuss Dream are...

• #dream on the Reason Discord.
• #webdev on the OCaml Discord.
• The OCaml Discuss forum.
• The development stream on Twitch.

Highlight @antron to poke @aantron specifically.

Contributing

All kinds of contributions are welcome, including examples, links to blogs, related libraries, and, of course, PRs! See CONTRIBUTING.md.

Acknowledgements

Dream is based on work by the authors and contributors of its many dependencies and their transitive dependencies. There are, however, several influences that cannot be discovered directly:

• Templates are inspired by ECaml from Alexander Markov and Embedded OCaml Templates from Emile Trotignon.
• Dream's handler and middleware types are simplified from Opium by Rudi Grinberg and contributors.
• The lower-level HTTP and WebSocket servers use Antonio Nuno Monteiro's forks and original works, with credit also due to their contributors, and Spiros Eliopoulos in particular, as the original author of the http/af family of projects.
• The API docs are instantiated by Soupault from Daniil Baturin.
• The name was inspired by Morph from Ulrik Strid, which was itself partially inspired by Opium.
• Raphael Rafatpanah and El-Hassan Wanas provided important early feedback.