RE: [boost] Re: FC++ formal review

From: Rozental, Gennadiy (gennadiy.rozental_at_[hidden])
Date: 2004-03-02 12:07:52

> > Actually the point of my remark is that would we be able to 
> write meta 
> > programs in imperative style instead of FP style 
> compilation would be 
> > much faster.
> 
> The slowness of metaprogram compilation has almost *nothing* 
> to do with the FP style of metaprogramming, and almost 
> everything to do with the accidental nature of the 
> metaprogram evaluation engine (using template instantiation). 

And why do we have so many template to instantiate? Exactly my point:
because we couldn't change type definition we could only create new one. How
many helper templates gets instantiated to remove const types from the
type-list? Should be none. So you are right: it has everything to do with
nature of metaprogram evaluation engine, which is FP based one.

>  In fact, you *can* write metaprograms in an imperative 
> style, given an appropriate framework designed to interpret 
> them correctly.  It'll be much slower than what we use today.

You have any grounds for this statement?

> > And Spirit framework would benefit from it the most.
> 
> I doubt that.  Parsing in particular has little to gain from 
> the use of mutable data.

I meant from compilation time standpoint.

Gennadiy.