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Title: Arrows in Haskell's HXT library
Proposer: Frank Birbacher
Type: Tutorial
Duration: 90 mins
Description:
The Haskell HXT library is an open source library to processe XML and it offers its operations as 'arrows.' Arrows are an abstraction from ordinary functions like monads abstract from regular values. The special class of list arrows allows a concise, yet strong syntax for traversing an object tree like an XML DOM tree. Even more, it allows filtering, modifying and extracting information from a tree. This makes the HXT library a simple to use tool for XML processing. But once the arrows are understood their power can be applied to other data structures as well.
The talk will introduce the basic concepts of the type class Arrow, how it abstracts from a function and how instances can be combined to form larger computations. Care will be taken to explain the overloaded operators for arrows that in the end will allow a concise syntax. The real key to understanding the HXT library are the sub classes ArrowList and ArrowTree. They define the main operations to traverse a tree. Further the talk will show how to use the HXT library to convert the XML output of the Subversion log command into an HTML document.