From: matz@... (Yukihiro Matsumoto)
Date: 2002-04-22T11:50:18+09:00
Subject: Re: blocks vs. Procs, closures as objects?

Hi,

In message "blocks vs. Procs, closures as objects?"
    on 02/04/21, foo@bar.null <foo@bar.null> writes:

|{ |x| x * x }.type      => Proc, or Block, or Method, or something...
|
|a block is apparently not an object in ruby, which i guess means that
|it's not an expression, either...

A block is not.  a Proc object is.  You can get a Proc by

  lambda{|x| x * x}
  proc{|x| x * x}
  Proc.new{|x| x * x}

|anyone care to explain the rationale behind this?

Several reasons:

  * performance: you can avoid object creation.  It used to hinder
    performance.

  * simplicity: blocks are mostly used for iterators or control
    structures, so that I felt it was better to make them look like
    other control structures.

							matz.