[Haskell-cafe] Re: Why is this strict in its arguments?

[Paulo J. Matos]

On Dec 5, 2007 12:16 AM, Aaron Denney <wnoise at ofb.net> wrote:
> On 2007-12-04, Paulo J. Matos <pocm at soton.ac.uk> wrote:
> > Hello all,
> >
> > As you might have possibly read in some previous blog posts:
> > http://users.ecs.soton.ac.uk/pocm06r/fpsig/?p=10
> > http://users.ecs.soton.ac.uk/pocm06r/fpsig/?p=11
> >
> > we (the FPSIG group) defined:
> > data BTree a = Leaf a
> >                    | Branch (BTree a) a (BTree a)
>
> Totally avoiding your question, but I'm curious as to why you
> deliberately exclude empty trees.
>
> Come to think of it, how can you represent a tree with two elements?
>

Good question. I think we were just trying to define a tree in the
meeting and everyone agreed on this representation.

> Wouldn't
>
> > data BTree a = Empty
> >              | Branch (BTree a) a (BTree a)
>
> be better?
>

Possibly :) I think that at the time nobody really cared about empty
trees! But for a really application we would have had to define them
probably. Now thinking about it, it seems like defining lists without
Null, strange, isn't it?

> --
> Aaron Denney
> -><-
>
>
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-- 
Paulo Jorge Matos - pocm at soton.ac.uk
http://www.personal.soton.ac.uk/pocm
PhD Student @ ECS
University of Southampton, UK