xml-lens-0.3.1: README.md

xml-lens
========

Lenses and traversals for [xml-conduit](http://hackage.haskell.org/package/xml-conduit).

Example
========

```haskell
> doc <- Text.XML.readFile def "examples/books.xml"

> doc ^.. root . named "books" ... named "book" . attributeIs "category" "Textbooks" ... named "title" . text
["Learn You a Haskell for Great Good!","Programming in Haskell","Real World Haskell"]

> lengthOf ?? doc $ root . named "books" ... named "book"
7

> doc ^? root . named "books" ... attributeIs "category" "Joke" ... named "title" . text
Just "Functional Ikamusume"

> doc & root . named "books" ... named "book" ... named "pages" . text <>~ " pages" & renderLBS def & BL.putStrLn
```

```xml
<?xml version="1.0" encoding="ISO-8859-1"?>
<books>
<book category="Language and library definition">
    <title>Haskell 98 language and libraries: the Revised Report</title>
    <author year="2003">Simon Peyton Jones</author>
    <pages>272 pages</pages>
    <price>£45.00</price>
</book>
<book category="Textbooks">
    <title>Learn You a Haskell for Great Good!</title>
    <author year="2011">Miran Lipovaca</author>
    <pages>360 pages</pages>
</book>
<book category="Textbooks">
    <title>Programming in Haskell</title>
    <author year="2007">Graham Hutton</author>
    <pages>200 pages</pages>
</book>
…
```

Tips
----

* Use [cosmos](http://hackage.haskell.org/package/lens-4.19.2/docs/Control-Lens-Plated.html) to traverse over all children
* You can do or-composition of traversals with [failing](http://hackage.haskell.org/package/lens-4.19.2/docs/Control-Lens-Traversal.html#v:failing)