[Haskell-cafe] Is lazyness make big difference?

[Kurt Schelfthout]

2007/2/15, Dougal Stanton <ithika at gmail.com>:
> Quoth Nick, nevermore,
> > According to one guy's analogy: the Real World is strict - in order to
> > drink tea, you have to put the cattle on the fire, wait until water
> > boils, brew tea and then drink. Not the cattle is put on the fire, water
> > boils and the tea is brewed when you take the empty cup to start
> > drinking. :-)
>
> I think the word you meant there is "kettle", since "cattle" are what
> get turned into burgers ;-) Still, the idea of water-boil-tea-brew
> happening by demand would probably save electricity in our
> energy-conscious world. Don't boil a full kettle for a single cuppa!

An example of real world laziness, and where it pays off, is maybe the
kanban system as used in manufactering:
http://en.wikipedia.org/wiki/Kanban

Not sure though if such so called real world examples actually add
much to the discussion. Ultimately I think you need both lazy and
strict evaluation; a reasonable default depends on the flavour of the
particular language. Given Haskell, it seems lazy by default is the
obvious choice (however I may feel that way simply because it _is_
that way :) )Strict just can't be the _only_ option, as it too often
is.

Kurt