From: "trans.  (T. Onoma)" <transami@...>
Date: 2004-10-09T01:41:28+09:00
Subject: Re: Range behavior (Re: [RCR] New [] Semantics)

On Friday 08 October 2004 09:43 am, trans.  (T. Onoma) wrote:
| Okay, planB is good. You are going the other way toward Range being
| continuous. That's fine, but really that should be called an Interval:
|
|   http://mathworld.wolfram.com/Interval.html
|
| Range really means something else.

Following this to logical conclusion. (IMHO) Elegant design would be along 
these lines:

  class Interval
    # not Enumerable
    def to_rng
      Range[self]
    end
    def each
      # coerce to Range, then each
      to_rng.each
    end
  end

  (0..5).class  #=> Interval

  class Range < Interval
    alias :enclose? :include?
    include Enumerable
    def self.[](*args)
      if args[0].kind_of?(Range) 
      # ...
    end
    def initialize(start, length)
      # ...
    end
    def each
      # based on start#succ
    end
  end

So a Range is a "temporal" Array, in contrast to an Array which is "spacal" 
--if you know what I mean.  Also, coercing Interval to Range in #each deals 
with most, if not all, compatibility issues (I think). The only thing the 
above appears to need is how to handle the disconnect between Interval#end 
and Range#length. There's no perfect "congruence", as we have already 
discussed, but it shouldn't be difficult to determine this, i.e. I see no 
reason Range can't also support termination proc.

T.