DSL for creating html structure straight with Elixir blocks:

    use WebAssembly
    builder do
      html do
        head do
          meta http_equiv: "Content-Type", content: "text/html"
          title "example"
        end
        body do
          div class: "container", id: :content do
            ul do
              for index <- 1..3, do:
                li "item #{index}"
            end
            random = :random.uniform(10)
            if random == 5 do
              text "Lucky! You got five"
            end
          end
          span [style: "smiling"], "that was nice"
        end
      end
    end

This results in a deeply nested list (aka iolist) which you can flatten or (better!) send to the socket as it is (via Plug & Cowboy for example).

Now what can be concluded from the example above:

• you produce HTML elements by using macros inside builder block
• non-void element can be used with "flat" content argument or with a do-block
• element with a do-block means nesting
• inside such a do-block you have access to full Elixir syntax
• element attributes go first (but are optional), then the content
• attributes are Elixir keywords
• underscores in attribute keys are translated to dash signs
• you can omit brackets around attributes when using do-block, but not when using flat form
• void HTML elements correspond to macros with attributes only, like meta above
• if you want to emit just text without surrounding html tags, simply use text macro.

For me it's beautiful. What about you?

• to have views in pure Elixir, without HTML templates
• to utilize Erlang's approach: you can feed sockets with iolists instead of one big binary produced by template engine

You can possibly mix different styles: code small snippets in WebAssembly and feed them to your partial templates, finally using your template engine to render the whole page.

WebAssembly is published on Hex, so just add {:webassembly, "~> 0.6"} to your deps and :webassembly to your apps in the mix.exs.

Using it with Plug is a no-brainer - you just pass the doc to send_resp/3:

defmodule Plugged do
  import Plug.Conn
  use Plug.Router
  use WebAssembly
  plug :match
  plug :dispatch
  get "/" do
    doc = builder do
      html do
        body do
          text "hello from Plug!"
        end
      end
    end
    conn
    |> put_resp_content_type("text/html")
    |> send_resp(200, doc)
  end
end

API details are available at hexdocs.

WebAssembly aims to have 100% test coverage.

As for releases 0.3.0 and above WebAssembly dialyzes with no warnings.

Loosely inspired by Markaby.

The code is released under the BSD 2-Clause License.