From: "Suraj N. Kurapati" <sunaku@...>
Date: 2008-05-28T12:24:49+09:00
Subject: Re: [PATCH] lambda with normal block syntax

David Flanagan wrote:
> Well of course--its Matz's language.  But let's engage the debate with 
> reasonable expectations.  And I'm just trying to point out that given 
> the stage of the 1.9 release, it is probably unreasonable to expect an 
> alternative to -> in 1.9.  The most that can reasonably be hoped for, in 
> my opinion, is the removal of the -> syntax.

Why is the addition of bare blocks considered so daunting?  Unlike 
the removal of ->, the addition of bare blocks is *fully* backwards 
compatible with both Ruby 1.8.x and 1.9.0-x!

For instance, whereas early adopters of 1.9.0-x need to change their 
code after -> removal, nobody needs to change their code after the 
addition of bare blocks.

I would *really* like the addition of bare blocks to be considered 
for Ruby 1.9.  This addition finally makes "functional programming" 
invisible to the user by making blocks into first-class citizens 
(literals) in Ruby syntax.

Just think of the developer mind-share this would capture, as Ruby's 
functional programming capabilities can be *explained* much more 
easily to a newcomer (without scaring them away[1] with "lambda"):

   Ruby has *code blocks* -- which are blocks of code that you can
   pass around and execute whenever and wherever you want.

This kind of explanation is reinforced by the fact that users *see* 
blocks being used _everywhere_:  iterators, thread bodies, etc.

Furthermore, what follows the POLS more than being able to *snatch* 
a block (yes, with your bare hands) and place it (and reuse it) 
anywhere in your code:

   a = [1, 2, 3]
   b = [4, 5, 6]

   # here's a traditional code block
   a.each {|x| puts 2 * x }

   # why can't I snatch it and reuse it?
   code_block = {|x| puts 2 * x }
   a.each &code_block

   # if code blocks are really literal functions...
   doubler = {|x| 2 * x }   # *snatch*
   printer = {|x| puts x }  # *snatch*

   a.each(printer(doubler)) # place

This kind of classic function composition, is made so simple and 
intuitive with bare blocks:  they are a fundamental and highly 
idiomatic building block in the Ruby language today.

To testify, I've been playing with bare blocks for the past two days 
and I find them to be an absolute treat to use, especially in the 
do..end form because the "do" gives a strong clue the code block is 
a function:

   # an "adder" *do*es something with x and y:
   # it adds x and y and returns the sum
   adder = do |x, y|
     x + y
   end

   # call the "adder" and ask it to *do* something with 1 and 2.
   # but what does the "adder" do?  see above
   adder.call(1, 2) #=> 3

Thanks for your consideration.

[1] Of course, this has been my unfortunate experience of trying to 
explain what lambda is to newcomers from C++:  their eyes 
glazed-over, thinking that it was mathematics (groan!) I guess.