From: Brian Candler <B.Candler@...>
Date: 2003-03-24T18:56:22+09:00
Subject: Re: Ruby lecture slides (was Strong advantages over Python)

On Mon, Mar 24, 2003 at 11:40:52AM +0900, Paul Prescod wrote:
> Brian Candler wrote:
> >...
> > 
> > You can write that almost exactly the same in Ruby of course: substitute
> > proc { |foo| ... } for lambda foo:
> 
> Right, you've wrapped the block in a function.

Well, a Proc object to be precise... the nearest equivalent Ruby has to a
'function' is a Method, and that's not quite the same thing.

> It strikes me as a minor 
> wart (of the same sort that all languages have) that if you want to pass 
> a single closure you use block syntax but if you want to pass multiple 
> you switch to procs. I guess that keeps the syntax simpler.

I think it's just for clarity and ease of use. I consider the passing of a
single block as syntactic sugar, because you can treat it as an explicit
Proc object if you so wish:

   def myfunc(&block)
     &block.call         # same as 'yield'
   end

It's just that so often all you want to do is pass a single block, and the
language syntax has been designed to handle that case in a particularly
easy-to-use way. It's much nicer to write

   3.times do |x|
     puts x
   end

than

   3.times(lambda do |x|
     puts x
   end)

Regards,

Brian.