On Tue, Jan 1, 2013 at 2:05 AM, dag.odenhall@gmail.com <dag.odenhall@gmail.com> wrote:

Use arrow notation and zeroArrow, like so:

{-# LANGUAGE Arrows #-}
import Text.XML.HXT.Core
getA =
hasName "a" >>> proc elem -> do
    text <- getText <<< getChildren -< elem
    if text == "Hello Two!"
      then getAttrValue "href" -< elem
      else zeroArrow -< ()

>>> runX $ readString [] "<html><a href='example.com/somelink.html'>Hello One!</a><a href='example.com/anotherlink.html'>Hello Two!</a></html>" >>> deep getA
["example.com/anotherlink.html"]

On Mon, Dec 31, 2012 at 3:36 PM, Mateusz Kowalczyk <fuuzetsu@fuuzetsu.co.uk> wrote:

Hello,
I'm not sure if this is the right place to ask this but here goes.

I'm currently working with HXT and I quite like it. There's one issue I
can't solve (at least now without some dirty, dirty hacking) and I'm
sure it's fairly simple.

Consider the following mark-up

<a href="example.com/somelink.html">Hello One!</a>
<a href="example.com/anotherlink.html">Hello Two!</a>

Now, what I'm trying to achieve is to get the href based on the text. I
can test for what the text is by traversing <a>s, then using the
getChildren >>> getText arrow. What I can't figure out is how to check
the text and then get the href as by the time I get to the text, I'll
further down the tree!

I imagine it would look something along the lines of
(getChildren >>> getText <?*> "Hello Two") `guards` getAttrValue
"href". <?*> is just a random operator I made up for illustration
purposes that works as a predicate over arrows.

Is this the right approach? Is there a built-in that already does what I want? It
seems like a common task...

Mateusz Kowalczyk

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