A Haskell newbie's guide to Snap, Part 3

This is a followup to Part 1 and Part 2.  Those posts covered the basics of using Snap and Heist, and their APIs for accessing data from the HTTP request and from the splice instance.  This post will show how to access SQL data with the HDBC package (in this case, we'll use PostgreSQL).  Along the way, I hope to give a better picture of how all the pieces fit together (though I'd welcome comments from experienced Snappers on how the code might be improved).  

A Haskell newbie's guide to Snap, Part 2

This post is an overdue followup to Part 1.  I'll try not to repeat much of that material; review that link if you need a refresher.  Here I'll show how to use Snap and Heist to save some data from an HTML form.  That will involve using Snap to pull POST/GET data from the request and then building HTML elements for the page with the Text.XmlHtml library. 

We'll use the same simple cheese database as our background.  This database has four columns: name, country, price, and stock.  We want to have a single page that lets us edit an existing cheese record or create a new one.  There will be two forms.  The first form lets us enter the name to edit/create, and has an Edit/Create button that fills data into the second form.  The second form has text inputs for each of the data columns, and a Save button.  When we first land on our page, we're at /cheese_template.  Pressing the Edit/Create button sends us to /cheese_template?name=Epoisses, and pressing the Save button sends us to /cheese_template?_task=save.