From: Rodrigo Rosenfeld Rosas <rr.rosas@...>
Date: 2011-11-28T10:05:55+09:00
Subject: [ruby-core:41341] Re: [ruby-trunk - Feature #5663] Combined map/select method

Em 25-11-2011 01:00, Nobuyoshi Nakada escreveu:
> Issue #5663 has been updated by Nobuyoshi Nakada.
>
>
> Rodrigo Rosenfeld Rosas wrote:
>> Nobuyoshi, wouldn't&:even? be equivalent to :even?.to_proc? I just find that the example reads better this way ;)
> They are different.
> &expr calls #to_proc method on the result of expr, to achieve a Proc object.
>
>> (1..10).grep(&:even?){|i|i+1}
> It's a syntax error.

Wow! Thanks! This is unexpected to me. I didn't know about the difference.

Anyway, I still didn't understand why (1..10).grep(&:even?) works, but 
(1..10).grep(&:even?){|i| i+1} not.

Actually, I didn't understand your explanation. You said that &expr 
calls #to_proc on the result of expr. What is the expr on each example? 
Is there any place I could further read about those differences?

Thank you, Rodrigo.