[Haskell-cafe] Re: Channel9 Interview: Software Composability and theFu ture of Languages

Yitzchak Gale gale at sefer.org
Thu Feb 1 05:28:38 EST 2007

On 1/31/07, Kirsten Chevalier <catamorphism at gmail.com> wrote:
> On 1/31/07, Bill Wood <william.wood3 at comcast.net> wrote:
> > On Wed, 2007-01-31 at 19:51 +1100, Donald Bruce Stewart wrote:
> >    . . .
> > >     foldl (\water dish -> wash water dish) soapywater dishes :: [Dishes]
> >
> > Nice example.  First, note that you can't get close with map -- you need
> > accumulation across the dishes.  Second, the correctness of this plan
> > depends on the rather strong frame axiom that no entity in the
> > environment is changed during a step of the fold, so no broken dishes.
> > Finally, that doesn't work so well when there are constraints on the
> > order that the dishes are washed, for example when washing the cruddiest
> > dishes first while there are more suds.

> It also assumes that there's necessarily a natural decomposition on
> the dishes, and if you think there is, you haven't seen my kitchen!

In my kitchen, there is a natural decomposition on the dishes.
Especially on the ones that have been at the bottom of the pile
for the longest time.


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