Em Sáb, 2009-09-26 às 16:14 +1000, Timothy S. Nelson escreveu:
>       I've been wondering about lenses recently.  The page at 
> http://www.seas.upenn.edu/~harmony/ seems to give an overview, and I know 
> that 
> augeas also uses lenses.
>       It seems to me that a grammar can be thought of as a one-way lens.  I 
> was wondering whether the bi-directional idea might be interesting in this 
> context.  It seems to me that, at the moment, when we want to do a format 
> conversion, we:
> -     Read the data in with a grammar
> -     Output the data with something like Form.pm
>       I'm wondering if there isn't some way that the whole thing can be 
> turned into lenses.
>       Anyway, I'm sort of half thinking out loud, and wondered if anyone had 
> any relevant thoughts.

I think this is an interesting addition to the old "Tree Transforming
Language" debate that once a year we remember to discuss. 

Basically, we could understand perl5+B::Deparse as composing a "lens",
but it's done pretty much in an ad-hoc way, which is fine for perl5,
since it's much more static (okay, that was before Devel::Declare)...

But in Perl 6, that is pretty much interesting, because we have
something pretty abstract, which is the STD parse tree, which needs to
be converted into some implementation's optree/bytecode/whatever.

but I'm sort of half thinking out loud as well ;)


  • Lenses? Timothy S. Nelson
    • Re: Lenses? Daniel Ruoso

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