Re: XSLT for Extensibility

>    How do you allow the user to plug in new tasks?
> 
>    This is a general problem I'm having, how do you create hooks,
>    callbacks, er, how do you create an XSLT framework?
> 

Read about FXSL. It is a system to build and use higher-order
functions in pure XSLT.

FXSL functions can be passed as parameters (callbacks) or returned as
results. They also are curried functions in that they allow for
partial application -- applying a function on less arguments than the
function accepts results in the return of another function, which
accepts only the missing arguments and then behaves as the original
function.

The latest version of FXSL for XSLT 2.0 allows one to wite
xsl:function 's in this way. Also, it is possible to create a HOF
wrapper around any other function, including the standard XPath 2.0
Functions and Operators and the standard XSLT functions and also
useful constructs.

FXSL provides such HOF wrappers for nearly all XPath 2.0 F & O's. This
means that XSLT 2.0 + FXSL is a functional programming system with
full support for higher-order function programming.

FXSL also provides its own implementation of almost all Haskell
Prelude functions (such as foldr, foldl, map, scanl, zip-with, split,
span, drop, filter, ... etc.), which serve as the kernel for building
other useful HOF.


>    --
> 
>    I asked elsewhere, and pipelines were suggested

This is naturally done in FXSL by functional composition. As result
otherwise difficlut problems can be solved in a one-liner XPath
expression.

Read more about FXSL at:

               http://fxsl.sf.net


Cheers,
Dimitre Novatchev.