> I don't see that functional programming is any different than 
> imperative programming in this regard: unless the CPUs SIMD 
> data structures are first-class objects (or have a first 
> class abstraction that is
> CPU-neutral) and useable in the platform APIs, the SIMD 
> instructions are just inaccessible: the result is our text 
> processing programs run slower
> (2 times? 10 times?) than they could. 

I think there is a difference: in a functional (stateless) language, far
more aggressive compile-time rewriting of expressions is possible, including
the ability to generate code that does multiple operations in parallel. This
kind of rewriting cannot be done in imperative languages because the
side-effects cannot be statically analysed. I think Intel are the only
people currently doing this kind of rewriting (for XSLT) in a way that goes
right through to generating code for specific hardware, but the potential is
there.

Michael Kay
http://www.saxonica.com/


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