From: Jacob Burkhart <igotimac@...>
Date: 2007-05-31T21:32:28+09:00
Subject: Re: Introducing the "it" keyword

consider the clarity of reading these:

with(v+1) do |a|
    with(x+2) do |b|
        return a if a+b < 10
    end
end

vs.

with:a(v+1) do
    with:b(x+2) do
        return a if a+b < 10
    end
end

with:var could be usefull in other scenrios as well, yes?

We could say that with:a(v+1) is just an abbreviation for with( :a => v+1 )
and with is just a method that has the magical ability to bind
variables in the scope of the block it's given. (so in this case bind
'a' with the value of 'v + 1')

am I crazy?


On 5/31/07, Jacob Burkhart <igotimac@gmail.com> wrote:
> Would a let or with construct be fast enough and memory efficient
> enough for those concerned about such things?
>
> def with(args*)
>     yield args
> end
>
> with( v + 1 ) do |it|
>     return it if it < 10
> end
>
> If this isn't fast enough or memory-efficient enough, then I would
> suggest we find a way to make the interpreter recognize or optimize
> such cases.
>
> Perhaps "with" could be provided by the language by default, and then
> we could support this line as syntactic sugar:
>
> return it if with(v+1) < 10
>
> or maybe:
> return it if with_it(v+1) < 10
>
> The interpreter would have to recognize and transform this into the
> equivalent with ... do ... end
>
> Or maybe we can go really crazy with the syntax, and support any name
> for the 'tmp' variable (and any number of temp variables) with the
> knowledge that if we use this syntax to assign them, the interpreter
> will know to transform and garbage collect appropriately.
>
> return it if with:it(v+1) < 10
>
> return a if with:a(v+1) < 10
>
> return a,b if ( with:a(v+1) + with:b(x*y) ) < 10
>