Make the location implicit

URLs are the addresses of the internet. Each URL points to a location and your user can go there. However on the internet the addresses are not that important to the users and browsers. Especially since we can read almost any page on such a location. So the location doesn't matter as long as we find what we expect.

The URL and the link text both build an expectation in us. The text and the URL will imply what we will find after we click the link. I think it makes sense to write links without showing the URL.

For example when I wrote some code and pushed it to GitHub, I could write it like this:

I posted my new code to GitHub: http://github.com/pstuifzand/pompiedom-river.

Or I could write:

I just released a new of version of Pompiedom, an rssCloud-enabled realtime river.

The second example explains what you will find when you click the link. Another reason for writing text instead of URLs is that the layout engine has more to work with when breaking lines, especially when using justified text.

Using user-generated HTML on webpages

Jeff on Coding Horror writes:

Among programmers of any experience, it is generally regarded as A Bad Idea (tm) to attempt to parse HTML with regular expressions.

You should read the rest of the article. I'm mostly of the same opinion about this as Jeff. Additionally I think that parsing HTML is a bad idea in the first place.

One of the examples Jeff gives for parsing HTML is sanitizing user input. The user input will be used on the website as comments for example. I think allowing people to write HTML and putting it on a webpage is the wrong way to go.

If you want to include user input in a web page there are only two ways to do it:

1. Encode all special HTML characters. You can start with <, >, &, " and '. If you encode these then people can send all the HTML they want, but it's encoded and will not affect your web page. For Perl I recommend the HTML::Entities module.

2. The other way to allow HTML is, on a page, where it is their own. If they want to break their own web page, they should be allowed to do that. This doesn't mean profiles on websites, but actual websites that are completly their own.. So you say it is HTML and then use the input verbatim.

If you want to include some kind of formatting for the input, you can use a markup language. Use a markup language that allows to specify as much formatting as you like, this could be a HTML-like language, that only transforms the tags that you want. Therest of the text should be HTML encoded.

First try Haskell web applications

I'm trying Haskell for writing Web applications. It should be really easy, but at the moment I'm missing the examples. The documentation doesn't really help for generating the XHtml.

The following bit of code is something that I found: Haskell and Web applications. The article contains a simple example. I changed the code in the example to use a table instead of the spans. This turned out to be really easy to do.

renderData :: (Data a) => a -> Html
renderData i = table << mapFields renderField i
    where renderField (name, val) =
                tr << [ (th << renderFieldName (name ++ ":")) ! [ align "left" ]
                      , td << (read val :: String) 
                      ] 

I added the call to read to remove the quotes around the values. The << operator adds the objects to the right as the children of the object to the left. Because of the way this is specified this can a list or a single object.

The ! operator adds an attribute to the object on the left.

There need to be more examples for Haskell that are easy to understand and change, because it is hard to understand the ways that functions work from the documentation (types and functions) alone.

I hope this will help some of you trying to write some Haskell code.