VLERange: a range in between BidirectionalRange and RandomAccessRange

[Steven Wawryk]

Sorry if I'm jumping inhere without the appropriate background, but I 
don't understand why jumping through these hoops are necessary.  Please 
let me know if I'm missing anything.

Many problems can be solved by another layer of indirection.  Isn't a 
string essentially a bidirectional range of code points built on top of 
a random access range of code units?  It seems to me that each 
abstraction separately already fits within the existing D range 
framework and all the difficulties arise as a consequence of trying to 
lump them into a single abstraction.

Why not choose which of these abstractions is most appropriate in a 
given situation instead of trying to shoe-horn both concepts into a 
single abstraction, and provide for easy conversion between them?  When 
character representation is the primary requirement then make it a 
bidirectional range of code points.  When storage representation and 
random access is required then make it a random access range of code units.