XMLW

January 30, 2015 · View on GitHub

XMLW is an Ur/Web library defining a monadic XML accumulator. It allows programmer to mix XML code and transactional logic in a single Writer-like monad.

Installing

This project depends on some git submodules, so the typical install sequence would be:

$
git clone https://github.com/grwlf/urweb-xmlw
cd urweb-xmlw
git submodule update --init --recursive
make

The Makefile builds ./lib.urp and certain tests in test/ folder.

Example

In the following example, the database query code is located very close to the place we render it's result. We no longer need to separate transactional actions from purely-functonal XML producer.

fun dnest st m =
  push_back (nest (fn x=><xml><div style={st}>{x}</div></xml>) m)

fun tnest m =
  push_back (nest (fn x => <xml><table>{x}</table></xml>) m)


fun main {} : transaction page =

  b <- run (

    push_back_xml (<xml><h1>XMLGen test</h1></xml>);

    dnest (STYLE "background:grey") (

      push_back_xml (<xml><h2>Nested DIV</h2></xml>);

      dnest (STYLE "background:white;margin:15px") (

        push_back_xml (<xml><h2>Innermost DIV+table</h2></xml>);

        tnest (
          push_back_xml
          <xml><tr><th>ID</th><th>S</th></tr></xml>;

          lift (debug "Lifting monad transactional works well");

          query_ (SELECT A.Id, A.S FROM a AS A)
          (fn r =>
            push_back_xml
            <xml><tr><td>{[r.A.Id]}</td><td>{[r.A.S]}</td></tr></xml>
          )
        )
      )
    )
  );
  return
  <xml><head/><body>{b}</body></xml>