From: Chad Perrin <perrin@...>
Date: 2007-07-19T06:17:21+09:00
Subject: Re: syntactic sugar buzz

On Thu, Jul 19, 2007 at 06:09:43AM +0900, Robert Dober wrote:
> On 7/18/07, Chad Perrin <perrin@apotheon.com> wrote:
> >On Wed, Jul 18, 2007 at 09:17:45PM +0900, dblack@wobblini.net wrote:
> >>
> >> My favorite slogan for Ruby is:
> >>
> >>   The triumph of balance over symmetry.
> >>
> >> It means, for example, that it might make sense for nil to have #to_s
> >> -- and that it still might *not* make sense for nil to have #split.
> >> One does not imply the other.  Every decision is made carefully, one
> >> at a time, in the interest of the usefulness of the system overall.
> >
> >That makes perfect sense, since the logical way to use split would be
> >with something like nil.to_s.split.  If you really want split to return
> >something "useful" from nil directly, I'd say add your own split to
> >NilClass and be done with it.
> It makes perfect sense, but it is an example ex nihilis as I was
> complaining about nil.to_i and Integer(nil), or am I in the wrong
> thread (has happened to me before :()?
> 
> >
> >
> >>
> >> That's why I don't care about symmetry or consistency (which I think
> >> in this case mean much the same thing).  We're lucky enough to have
> >> Matz hand-crafting the language with the greatest care; I think that's
> >> a higher-percentage prospect than a principle of uniformity :-)
> >
> >I care about consistency -- in a way that makes sense, of course.  I
> >don't see how nil lacking a split() violates that.
> Nor do I, nor did I say so, I just wanted to say, hey if nil has to_i,
> it can have split too, that would be no big deal at all.

Unless nil.split simply returned nil, like:
  Class NilClass
    def split
      self
    end
  end
. . . I don't see how NilClass.split could reasonably be incorporated as
a standard part of the language.  The only other alternatives that
spring to mind would be to return false (as though split() were a
boolean test in this case) or to return an empty list.  I don't think
either of those really works very well, since returning false doesn't
bring anything new to the table and an empty list would be turning
nothing (nil) into something (even if it's an empty something), which is
a severely broken approach in my opinion.

Unfortunately, returning nil is also a little troublesome, since split()
is expected to return a list, but nil is definitely not a list.

Maybe nil.split should just return an exception.  Oh, wait . . .

-- 
CCD CopyWrite Chad Perrin [ http://ccd.apotheon.org ]
Paul Graham: "Real ugliness is not harsh-looking syntax, but having to
build programs out of the wrong concepts."