[xsl] RE: mapping (Was: Re: Re: . in for)

[Dimitre Novatchev <dnovatchev@xxxxxxxxx>]

DPawson at rnib dot org dot uk wrote:

> Jeni wrote
> > > This example could be handled with a mapping operator:
> > >
> > >   <xsl:variable name="emps"
> > >     select="//employee[@dept = ($departments -> lower-case(.))]" />
> 
> +1 on mapping, but I dislike the above syntax Jeni.
> Scheme gives (map fn sequence).
> 
> How about 
> 
> select='map lower-case(.) $departments'/>
> or
> select='map (lower-case(.) $departments)'/>
> 
> or does this go against the idea of extending keywords?


In both cases lower-case(.) is a value and not a function. The map function requires
a function as an argument as in:

select='map (lower-case(), $departments)'/>

This would be possible if the XPath 2.0 WG decides for higher-order function support
in XPath 2.0.

Many people already support this idea. A language with higher-order functions can be
simple and powerful, as this is described in:

"Higher-order function support as means to reduce the "standard"
operators/functions. "

http://aspn.activestate.com/ASPN/Mail/Message/xsl-list/967679

Cheers,
Dimitre Novatchev.
 

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