app.js

// ...
var templates = require('./haml_loader');
// ...

// List all items, return html
app.get('/items/all',function(req,res){
  Item.find().all(function(items){
    var item_haml = templates['item'];
    var output = "";
    for(var i=0; i<items.length; i++){
      var item = items[i];
      // the 'item' template requires two locals, the item name, and the item description
      output += item_haml({name:item.name,description:item.description});
    }
    res.send(output); // returns the html
  });
});