XSLT Cookbook

Chapter 14. Generic and Functional Programming

The brilliant moves we occasionally make would not have been possible without the prior dumb ones.

—Stanley Goldstein

Introduction

This chapter renders all previous chapters moot. Okay, maybe this is a slight exaggeration. The fact is that the examples in previous chapters solve the particular problems they address. They are also useful for didactic purposes. If an example does not solve a problem you face, it might point the way to a solution. The desired solution could be a small modification of the code or a reapplication of the same techniques.

This chapter sets its goals a little higher. It presents examples that solve a very broad range of problems without requiring customization of the example’s core code. Those of you who are familiar with C++, and specifically the Standard Template Library (STL), already know the power you can obtain by creating generic code (generic algorithms) and reusing them in various contexts. Others who use functional programming languages (e.g., Lisp, ML, or Haskell) also know of the great power obtained through the creation of higher-order functions: general-purpose functions that are specialized by accepting special purpose functions as arguments. This chapter shows that XSLT, although not specifically designed as a generic or functional language, has inherent capabilities to enable similar usage.

Warning

The techniques used in this chapter stretch the abilities of XSLT quite a bit. Not everyone will ...