Working With Lists in HXT

Question

I'm going crazy trying to use the simple >>. and >. functions defined here.

I want to get the length of all the text for a node in HXT. I'm using this:

runX (doc //> hasName "div" //> text >>. unlines)

Where doc is my XmlTree Arrow.

This gets me all the text for all divs (including text in any children they have). It gets the text as a string because I'm using unlines. Now I want to get the length of that string, so I try:

runX (doc //> hasName "div" //> text >>. unlines >. length)

And HXT seems to magically convert my string back into an array, because I get this:

[0,17,0,20,0,11,...]

What I want is all those Ints summed up. How would I do this?

Update:

The text function is defined like this:

text = deep (getChildren >>> getText)

I figured out that if I skip the getChildren bit, this works correctly:

text = deep getText

As long as I only have one div element. If I have multiple div elements, I get back an array with the length for each element.

Answer 1

Consider the next two examples:

Prelude Text.XML.HXT.Core> flip runLA undefined $ (constL [1, 2] >>>  arr id) >>. take 1
[1]
Prelude Text.XML.HXT.Core> flip runLA undefined $  constL [1, 2] >>> (arr id  >>. take 1)
[1,2]

The difference is only in brackets. Without brackets it will work as the second example. So you have the issue cos different fixities.