[xsl] Vendor extensions for XSLT - higher order functions

[Justin Johansson <procode@xxxxxxxxxx>]

Hi xsl-list,

I am curious to know why some XSLT vendors have implemented one or more
XSLT extension functions with their product to make for the implementation
of higher-order functions (HOF) in XSLT.

Given that Dimitre Novatchev of FXSL fame published his functional programming
library for XSLT, namely FXSL, as early as XSLT 1.0, refer

http://fxsl.sourceforge.net/articles/FuncProg/Functional%20Programming.html

why would an XSLT vendor implement similar functionality as XSLT extension
elements and/or functions and not just recommend using the FXSL library.

AFAIK, FXSL is 100% compatible with both of the W3C XSLT 1.0 and 2.0
recommendations.  Surely one would think it undesirable to implement
related functionality as a non-W3C extension if similar functionality
already existed in a 100% compliant XSLT library.

Do Altova and Apache XSLT products have HOF extensions for XSLT?
I am aware that Saxonica offer it (via the saxon:function extension function)
in Saxon-SA but am not sure about the others.

Best wishes to all.








Justin Johansson