Re: [Ocaml-lib-devel] Dllist

[Christophe T. <Chr...@um...>]

On Fri, 27 May 2005, John Skaller wrote:
> 
> On Fri, 2005-05-27 at 12:06 +0200, Christophe TROESTLER wrote:
> > On Thu, 26 May 2005, Brian Hurt <bh...@sp...> wrote:
> > > 
> > > On Wed, 25 May 2005, Christophe TROESTLER wrote:
> > > 
> > > > Is there a good reason (aside from implementation easiness)
> > > > not to allow Dllist to be empty?  IMHO, empty lists are very
> > > > useful and it is rather an hindrance that Dllists cannot be.
> > > 
> > > My original implementation did allow for empty lists, but it got 
> > > overridden.
> > 
> > Where?  The CVS version does not seem to allow it.  
> 
> Originally, the dlists had 'header' objects.

No sure what you mean precisely by that.

> I think I'm responsible for arguing that this is too complex, the
> lists should be made from a single simple data structure.

Can you explain a bit more your point?  IMO, when one designs a
library for wide use, one should take care about simplicity of the
interface, usability and (if relevant) performance.  If that means a
bit more of coding, that's not a big deal.  Here the usability is at
stake: I think a [mutable,...] list that cannot be empty is not nearly
as useful as one that can.

> As such, an empty list cannot be represented: use dlist opt
> if you want possibly empty dlists.

And redefine every single function of the module to cope with that!
That defeats the purpose of using the library doesn't it.

ChriS