VLERange: a range in between BidirectionalRange and

[Steven Schveighoffer]

On Sat, 15 Jan 2011 17:19:48 -0500, foobar <foo at bar.com> wrote:

> I like Michel's proposed semantics and I also agree with you that it  
> should be a distinct string type and not break consistency of regular  
> arrays.
>
> Regarding your last point: Do you mean that a grapheme would be a  
> sub-type of string? (a specialization where the string represents a  
> single element)? If so, than it sounds good to me.

A grapheme would be its own specialized type.  I'd probably remove the  
range primitives to really differentiate it.  Unfortunately, due to the  
inability to statically check this, the invariant would have to be a  
runtime check.  Most likely this check would be disabled in release mode.

This can cause problems, and I can see why it is attractive to use strings  
to implement graphemes, but that also has its problems.  With grapheme  
being its own type, we are providing a way to optimize functions, and  
allow further restrictions on function parameters.

At the end of the day, perhaps grapheme *should* just be a string.  We'll  
have to see how this breaks in practice, either way.

-Steve