[erlang-questions] If you are homesick for object.selector

Darach Ennis <>
Sat Jan 26 01:13:27 CET 2013


Hi guys,

I have no beef with these parse transforms you speak of. But, I haven't
used them so will stop at wishing them good health - maybe pencil in a few
hours
with them as penance for my non-erlangy sins too. :)

I think folk new to erlang will likely be familiar with XML Path though. So
picking up a variant based on XPath 1.0 would be fairly natural. I'm
clutching
at straws here, but maybe parse transforms have a role to play here too.

I see no reason why Joe's selector couldn't be bound as function in some
kind of erlangy xpath for tuples. So we would get something like:

P = tpath:scan(X, "/top/a/x/p").

No hints required. The path is explicit. The hints in the parse transform
would equate to the following XPath

P = tpath:scan(X, "/top//p").

If the structure changed so there was a list of x's and we just want the p
from the first occurrence?

P = tpath:scan(X, "/top/x[first()]/p").

Maybe I want all p's matched on some guard or filter?

P = tpath:scan(X, "/top/x[key =/= 'corba']/p[@a]").

And, maybe parse transforms, funs could be plugged in too ...

P = tpath:scan(X, "some_module:some_fun(//p[@a)").

Perhaps I'm stuck with the xpath style bag because it's familiar
and I've been using it for ~14 years. The cool young kids might
prefer a more jsony selection experience. I could live with that:

P = jsony:scan(X, "top.a.x.p");

But this: #top{a=#one{x=#foo{p=P}}} = X

I can barely parse it visually. It's too noisy, too busy.

Cheers,

Darach.

On Fri, Jan 25, 2013 at 10:37 PM, Raoul Duke <> wrote:

> please contribute to getting LFE back in motion.
> $0.02,
> sincerely.
> _______________________________________________
> erlang-questions mailing list
> 
> http://erlang.org/mailman/listinfo/erlang-questions
>
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